You explain things so clearly that my professor can't even make clear in a 3 hour lecture. I was so confused about aspects of digital logic but now I understand after watching some of your videos, thank you so much.
i was so confused about the subtraction using 2s complement but your video was so excellent that now i able to solve properly.You explain much better than my teacher,Thank You:)
To clarify bit further on what sir mentioned at 05.30, the addition becomes simplified when we assume 5 bit number system (as representing 9 in 2 complement notation needs 5 bits - the 4 bit range is from [-8, +7]) A = 01001 = 9;B = 00100 = 4; Y = A - B = A + (-B) = 01001 + (-00100) = = 01001 + (11100) = [1]00101. In this notation, the overflow bit (in the square bracket) can always be discarded and the sign of the most significant bit shows the sign of the number. 0 means positive and 1 means negative ---- Just as a check, B-A = 00100 - 01001 = 00100 + (-01001) = 00100 + (10111) = 11011 = -(00101) = -5 ---- (i) Check minimum number of bits required (ii) Convert everything into 2s complement notation in those number of bits (iii) Add -------- In this way, overflow only happens when MSB of the two numbers added is the same, and they are of opposite sign to the MSB of the result obtained.
for 3rd problem i think --> (+15) in 5-bit = 01111 so now (10110) -(01111) = 00111 in simple binary substraction means(A-(+B)) and with methoad two means (A+(-B)) you should sum 10110 with (-15) so (10110)+(10001) = 00111 so with two methoad +7 in 5-bit is 00111
The video is very good. I thought I could add some details for the truly nerdy, and for those who have an interest in how computer hardware does binary arithmetic, particularly subtraction. If you are new to binary, I suggest you skip this posting. There needs to be a way to represent negative numbers. There are three common ways: (1) Sign magnitude (2) One's complement (3) Two's complement; this is by far the most common, and the description follows: All of the explanation will be given assuming 4-bit words. Extending the description to 32 bits (or n bits) is left as an exercise for the reader. (LOL, don't you just hate it when instructors say that?) The 4 bits have the weights: -8, +4, +2, and +1. Note: --- Only the left most bit (the sign bit, the most-significant-bit MSB) has a negative weight; All the other bits have positive weights. --- If you set any bit to a 1 (except for the sign bit), the number becomes more positive (or less negative). --- The zero value is represented by 0000 --- All ones, 1111, has the value -1. (Since -8+4+2+1 = -1). To get the negative of a number (that is, to get -N given N), the rule is "complement all the bits and add 0001". First, define the bit-complement operator ~ to be: "Change each 1 to a 0 and each 0 to a 1". Examples: ~0000 = 1111, and ~1111 = 0000 ~0001 = 1110 ~1010 = 0101 Proof: note that N + ~N = 1111 = -1 Example: 0101 + ~0101 = 0101 + 1010 = 1111 = -1 Rearrange: ~N = -1 - N Rearrange: ~N + 1 = -N Finally: -N = ~N + 1 (QED) Examples using the complement+1 negation rule: +1 = 0001; -1 = ~0001 + 1 = 1110 + 1 = 1111 -1 = 1111; +1 = ~1111 + 1 = 0000 + 1 = 0001 +5 = 0101; -5 = ~0101 + 1 = 1010 + 1 = 1011 -5 = 1011; +5 = ~1011 + 1 = 0100 + 1 = 0101 0 = 0000; -0 = ~0000 + 1 = 1111 + 1 = 0000 (Notice: negating 0000 results in 0000.) And finally, negating twice returns the original number, a requirement. Now any two numbers, positive or negative, can be added or subtracted. To subtract a number, first take its negative (using the complement+1 rule given above) and then add. NO "BORROWING" IS EVER NECESSARY. The subtraction method used by hardware inside a computer CPU is: Change the subtraction problem to an addition problem (by negating the subtrahend using the complement+1 rule), then add, propagating the carries right to left. Note that the longer a computer word is, the more carries need to be propagated. The time to propagate the carries is proportional to the length of the word, O(length), which is slow for long words. There are "carry skipping" methods which reduce the carry time to O(log(length)), but these methods are another topic. Addition and subtraction can cause the integer overflow exception: -- If two positive numbers added result in a negative (MSB=1) sum, overflow has occurred. -- If two negative numbers added result in a positive (MSB=0) sum, overflow has occurred. Adding a positive number to a negative number never results in overflow. The negative of 1000 (= -8) results in 1000 and overflow, since the largest positive number is 0111 = +7. In hardware, it is easy to calculate overflow by looking at the carries into and out of the MSB: Overflow = ExclusiveOR(CarryIntoMSB, CarryOutOfMSB). Note that there is always a "strange" number for any of the three number systems: --- Sign magnitude has the number 1000 = 0000 (-0 = +0) since the MSB is the sign and has no value; there is no +8 or -8. --- One's complement has the number 1111 = 0000. Again, -0 = +0, and there is no +8 or -8. --- Two's complement has the number 1000 = -8, but there is no +8; the largest positive number is 0111 = +7. Two's complement has the "strange" number in the most out-of-the-way place, so it rarely causes a problem. The other two systems have the "strange" number at zero, which causes all-to-frequent, and unexpected, computational difficulties.
3rd problem You can't represent 1111 (15) in 2's complement just by 4 bits. So, make it 01111 --> 1's complement --> 10000 --> 2's complement --> 10001 Now, A + (-B) = 10110(22) + 10001(-15) = 100111 --> MSB discarded for the same logic --> 00111 (7)
@@theb4stguy332 because A is a 5 bit number and B is a 4 bit number, therefore to convert B into a 5 bit number, we add up the zero to the extreme left
No this method is wrong you have to take direct 2's compliment or else you would get stuck in 2nd problem where also (1110) is 14 so according to your approach (0111) -(1110) taking 2's of 14 will be 10001 Then adding you will get 11001 which is +ve 9 which is wrong ❌ As 0111(7) -1110(14) = -7 not +9
Can you say the answer of the question given below? -8-4=-12. I cannot perform this substraction by using binary 2's compliment Using the method which sir told.... Kindly if you can pls solve it
summary of process is: 1) do 2's complement on the 2nd number. 2) then add 1st number and 2's complement of 2nd number 3) if the result's sign bit is 1, then the result is positive. Ignore the sign bit, we get our answer If the result's sign bit is 0, then the result is negative. Ignore the sign bit, do 2's complement on remaining part. then, we get our answer
Im pretty sure Ex2 is wrong. Using the 2's complement representation, 0110 in binary is equivalent to +6 in decimal, while 1011 in binary is equivalent to -5. So in deicmal number system, the task is to perform the following subtraction: +6 -(-5) = 11.
S M yeah I was always confused with questions like this one. if u left it as -7 or put it back to +7?? I just looked at the original question. 7 - 14 = -7, hence why I left it in its 2s complement form (1001)
0111 + 0010 (2's complement of 1110) --------------------- 1001 ( now as there is no carry the result have to be converted in 2's complement form) ---------------------- hence the 2's complement of 1001 will be +7 i.e 0111. for 3rd question could you explain me ...
@@achchhelalgupta3176 for 3rd ques answer is 00111 B is 01111 2's of B will be 10001 10110 +10001 ------------ 100111(final carry is one ) so neglect 1 answer will 00111
At 5:42 you are mistaken, If the sign bit is “0”, this means the number is positive in value. If the sign bit is “1”, then the number is negative in value.
U said the carry leads to overflow but u add a 4 bit number which doest fall into that range. Sir actually we are dealing with signed numbers so 1001 is a negtive number so we should not guess the number directly and take 2's complement . So 1001 is -7 and 1100 is -4 and subtrating them we will get -3 101 or 1101 right?
sir aapne last video m kha tha 1's comp. of A is -A and now in this video 2's comp. of A is -A......but 1's and 2's comp. of 6 is not equal explain......
Sir, in previous (last) video you have said that 1's complement was negative form of number but in this you were saying that 2's complement was negative form of a number.... So which one is correct....
u said in previous lectures that....1 in signed bit indicates negative number....but here u consideres 1 as signed bit represents positive...how ...can any one make me clear??
yeah, Actually in four-bit binary we decide by MSB if MSB is 1 then its negative number but here we are deciding whether it is positive or negative by overflow, which is a different thing, I think now you can understand the difference between both
Vasu Deva Rao no you can't call , this theory is different, if you subtract( 13 )- (4) you will get (11001) in this you can see answer is 9 and overflow and msb is 1 .but being msb 1 you can't call this negative in this theory ;)
Sir when I substracted -48-23 (-48)+(-23)=-71 11010000 is 2's com.. of 48 11101001 is 2's complement of 23 Adding both we get 1 10111001 so we got carry 1 and is case of overflow and I neglected 1 the answer should be 10111001 which is not equivalent to -71 You said we need to take 2's complement of result when we don't get carry. If we get carry we simply ignore it and that is the answer but here even after neglecting Carry we don't get the answer please help sir I request you
I am having same type of doubt ... Like -8-4 =-12. On performing 2's complement I am getting a carry and if I ignore the carry the ans which I am getting is not the correct ans... So pls if you both get the solution of this problem then pls give a reply
Anas Khan The result which was obtained was negative and in its 2's complement form. So, to know the magnitude of the result (in this case +5), you have to perform the 2's complement of it(here -5).
Let me make your lives' easier: Subtraction with Complements The direct method of subtraction taught in elementary schools uses the borrow concept. In this method, we borrow a 1 from a higher significant position when the minuend digit is smaller than the subtrahend digit. The method works well when people perform sub- traction with paper and pencil. However, when subtraction is implemented with digital hardware, the method is less efficient than the method that uses complements. The subtraction of two n‐digit unsigned numbers M - N in base r can be done as follows: 1. Add the minuend M to the r’s complement of the subtrahend N. Mathematically, M+(r^n -N)=M-N+r^n. If M > or = N, the sum will produce an end carry r^n, which can be discarded; what is left is the result M - N. If M
My suggestion is to forget about one's complement arithmetic. Yes, it is sometimes used, but two's complement is FAR more common. To get the two's complement of a number, change all the 1's to 0's, change all the 0's to 1's, and then add 1. You must always add the 1. This works for both positive and negative integers.
Sir, I am still confused with overflow. Based on your condition for overflow, the example 1 will be indicated no overflow, since x'y'z+xyz'=1'0'0+100'=010+101=0 no overflow, but in your first example, you said it was overflow. Are we supposed to consider the discarded "1" as the sign of result? even though, the discarded "1" is considered as the sign bit of result, it will be like this: 1'0'1+101'=011+100=0+0=0. it is still 0, which is no overflow in terms of your condition for overflow.
I don’t understand that for the sign bit of 1 is positive and 0 is negative. To my mind, it’s should be the opposite. Would anyone help clarify this situation please???
so for example 2, I got the same answer when I subtracted 1 and THEN took the 1's compliment of the result. Is this okay to do or did it just work out in this example? Thanks
8-bit 2s complement binary numbers: 121 - 67 ? Is it overflow? It seems I got an answer 11111111 with discarding 11 .Did you have to ignore any carry bits?
I'm not very experienced with the theory behind the subject but I'm pretty sure it has to do with the fact that when we use 2's complement we split the number of possible combinations into two sides, one side for the positives and one for the negatives. If you imagine it as a circle where 0000 = 0, 0001=1 and so on then if we travel in the opposite direction of the circle we travel along our negative side, IE from 0000 if we go left we get 1111 which is equal to -1 and from there 1110 will be equal to -2 etc. pherricoxide.files.wordpress.com/2008/09/binary_circle2.jpg
You are confusing 2s complement with unsigned numbers. A combination of bits may have different meanings in different number systems (unsigned vs 2s complement) the same way a combination of letters may have different meanings in different languages. A number in 2s complement has two parts, a sign bit and the number itself. It is true that 1011=11 if you were discussing unsigned binary numbers, but for 2s complement recall that the leftmost bit is the sign, so the leading 1 is actually a negative sign and not a number at all.
well done NESO...I have a question and will appreciate if anyone answer it... to perform -7-3 we will do (-7)+(-3) 7 in Binary = 0111 in 2's complement it is -7 = 1 0 0 1 3 in Binary = 0011 in 2's complement it is -3 = + 1 1 0 1 ________ 1 0 1 1 0 NOW WE GET A FINAL CARRY THAT IS 1 THE ANSWER SHOULD BE RIGHT AND IN ITS TRUE FORM..IT SHOULD GIVE US 1010 THAT IS 10....but it is not giving us right ans...help will be much appreciated
I know we get 1010 we get do the 2's complement of 0110...but my confusion is how to know that we need to convert back the ans...in the first example....you didnt convert the answer...in second you did..why we need to convert our ans in my case when we have final carry = 1
When we need to convert our answer back into 2's comp...in your step 3 you said if we get a F.C = 1 we dont need to change answer as it is in true form...but when we do -7-3 we get a F.C...and we need to convert it back in order to cross check
that is why i am asking...i need to cross check to get full marks..9-4 = 5 = 0101 that is correct.... but -7-3 = 0110.....how come we know that answer is correct...??when we convert our answer only if we get F.C = 0.
i dont understand a point. In this video you said that the 2 compliment of a number is his negative. But in the previous video, you said the same thing with 1 compliment! So what is the difference???
Sir i am aktu btech first year student and i solved another questions through this method but my professor told me that this is not right way to solve plz guide me from where I need to learn the method which supports the concept of Fellercher standard book plz 🙏🙏🙏🙏🙏🙏🙏 if anyone now about this plz guide me
You explain things so clearly that my professor can't even make clear in a 3 hour lecture. I was so confused about aspects of digital logic but now I understand after watching some of your videos, thank you so much.
Fr he does
@kelseywhite1333
holy shit ! sweety
where you from ?
i was so confused about the subtraction using 2s complement but your video was so excellent that now i able to solve properly.You explain much better than my teacher,Thank You:)
OH MY GOD, ARE YOU PROFESSOR YOU? YOU EXPLAINED THIS THING IN 30 SECONDS WHILE I CAN'T EVEN LEARN IN 3 MONTHS IN LECTURE CLASS I THOUGHT I'M STUPID
Me too😌
My book has given the link of this video
@@yama_tv_69 wch book?
Computer for you with AI
ye sab asan hai but bohot practice ki jarorat hai nahi to bhul jata hu
To clarify bit further on what sir mentioned at 05.30, the addition becomes simplified when we assume 5 bit number system (as representing 9 in 2 complement notation needs 5 bits - the 4 bit range is from [-8, +7])
A = 01001 = 9;B = 00100 = 4;
Y = A - B = A + (-B) = 01001 + (-00100) = = 01001 + (11100) = [1]00101.
In this notation, the overflow bit (in the square bracket) can always be discarded and the sign of the most significant bit shows the sign of the number. 0 means positive and 1 means negative
----
Just as a check, B-A = 00100 - 01001 = 00100 + (-01001) = 00100 + (10111) = 11011 = -(00101) = -5
----
(i) Check minimum number of bits required
(ii) Convert everything into 2s complement notation in those number of bits
(iii) Add
--------
In this way, overflow only happens when MSB of the two numbers added is the same, and they are of opposite sign to the MSB of the result obtained.
as always Saved my time after hours of researching
اهلييين سعوديين في كل مكان ماشاءالله
thanks a lot for this ... everyone had complicated this so much... but u really helped me to clear my concepts.... it helped a lot for my exam...
for 3rd problem i think --> (+15) in 5-bit = 01111 so now (10110) -(01111) = 00111 in simple binary substraction means(A-(+B)) and with methoad two means (A+(-B)) you should sum 10110 with (-15) so (10110)+(10001) = 00111 so with two methoad +7 in 5-bit is 00111
Yes 👍🏻 right same ans
The video is very good. I thought I could add some details for the truly nerdy, and for those who have an interest in how computer hardware does binary arithmetic, particularly subtraction. If you are new to binary, I suggest you skip this posting.
There needs to be a way to represent negative numbers. There are three common ways:
(1) Sign magnitude
(2) One's complement
(3) Two's complement; this is by far the most common, and the description follows:
All of the explanation will be given assuming 4-bit words. Extending the description to 32 bits (or n bits) is left as an exercise for the reader. (LOL, don't you just hate it when instructors say that?)
The 4 bits have the weights: -8, +4, +2, and +1. Note:
--- Only the left most bit (the sign bit, the most-significant-bit MSB) has a negative weight;
All the other bits have positive weights.
--- If you set any bit to a 1 (except for the sign bit), the number becomes more positive (or less negative).
--- The zero value is represented by 0000
--- All ones, 1111, has the value -1. (Since -8+4+2+1 = -1).
To get the negative of a number (that is, to get -N given N), the rule is "complement all the bits and add 0001".
First, define the bit-complement operator ~ to be: "Change each 1 to a 0 and each 0 to a 1". Examples:
~0000 = 1111, and ~1111 = 0000
~0001 = 1110
~1010 = 0101
Proof: note that N + ~N = 1111 = -1
Example: 0101 + ~0101 = 0101 + 1010 = 1111 = -1
Rearrange: ~N = -1 - N
Rearrange: ~N + 1 = -N
Finally: -N = ~N + 1 (QED)
Examples using the complement+1 negation rule:
+1 = 0001; -1 = ~0001 + 1 = 1110 + 1 = 1111
-1 = 1111; +1 = ~1111 + 1 = 0000 + 1 = 0001
+5 = 0101; -5 = ~0101 + 1 = 1010 + 1 = 1011
-5 = 1011; +5 = ~1011 + 1 = 0100 + 1 = 0101
0 = 0000; -0 = ~0000 + 1 = 1111 + 1 = 0000 (Notice: negating 0000 results in 0000.)
And finally, negating twice returns the original number, a requirement.
Now any two numbers, positive or negative, can be added or subtracted.
To subtract a number, first take its negative (using the complement+1 rule given above) and then add. NO "BORROWING" IS EVER NECESSARY.
The subtraction method used by hardware inside a computer CPU is: Change the subtraction problem to an addition problem (by negating the subtrahend using the complement+1 rule), then add, propagating the carries right to left. Note that the longer a computer word is, the more carries need to be propagated. The time to propagate the carries is proportional to the length of the word, O(length), which is slow for long words.
There are "carry skipping" methods which reduce the carry time to O(log(length)), but these methods are another topic.
Addition and subtraction can cause the integer overflow exception:
-- If two positive numbers added result in a negative (MSB=1) sum, overflow has occurred.
-- If two negative numbers added result in a positive (MSB=0) sum, overflow has occurred.
Adding a positive number to a negative number never results in overflow.
The negative of 1000 (= -8) results in 1000 and overflow, since the largest positive number is 0111 = +7.
In hardware, it is easy to calculate overflow by looking at the carries into and out of the MSB:
Overflow = ExclusiveOR(CarryIntoMSB, CarryOutOfMSB).
Note that there is always a "strange" number for any of the three number systems:
--- Sign magnitude has the number 1000 = 0000 (-0 = +0) since the MSB is the sign and has no value; there is no +8 or -8.
--- One's complement has the number 1111 = 0000. Again, -0 = +0, and there is no +8 or -8.
--- Two's complement has the number 1000 = -8, but there is no +8; the largest positive number is 0111 = +7.
Two's complement has the "strange" number in the most out-of-the-way place, so it rarely causes a problem.
The other two systems have the "strange" number at zero, which causes all-to-frequent, and unexpected, computational difficulties.
Thank you Neso Academy 🌟 Your presentation was amazing! Take a bow!
1) 0010 +ve in true form
2)1001 -ve in 2's complement form
3)00111 +ve in true form
In 2nd question the final ans is 0111 right?
@@nishantpandey5435 no it's 1001 only!
@@snehilgupta6201 ok i got it....brother...🤟🤟🤟
@@snehilgupta6201 How? I got 0111
@@snehilgupta6201 How? I got 0111
3rd problem
You can't represent 1111 (15) in 2's complement just by 4 bits. So, make it 01111 --> 1's complement --> 10000 --> 2's complement --> 10001
Now,
A + (-B) = 10110(22) + 10001(-15) = 100111 --> MSB discarded for the same logic --> 00111 (7)
Thanks bro
Why do we convert 1111 to 01111 at start?
@@theb4stguy332 because A is a 5 bit number and B is a 4 bit number, therefore to convert B into a 5 bit number, we add up the zero to the extreme left
@@fatimatuzahra8945 👍
No this method is wrong you have to take direct 2's compliment or else you would get stuck in 2nd problem where also (1110) is 14 so according to your approach
(0111) -(1110) taking 2's of 14 will be 10001
Then adding you will get 11001 which is +ve 9 which is wrong ❌
As 0111(7) -1110(14) = -7 not +9
Really amazing u r sir
I nearly completed everything for my digital electronics from your lectures sir
Thank u sir
Can you say the answer of the question given below?
-8-4=-12. I cannot perform this substraction by using binary 2's compliment
Using the method which sir told....
Kindly if you can pls solve it
9:30, a practical example? x'y'z + xyz'
summary of process is:
1) do 2's complement on the 2nd number.
2) then add 1st number and 2's complement of 2nd number
3) if the result's sign bit is 1, then the result is positive. Ignore the sign bit, we get our answer
If the result's sign bit is 0, then the result is negative. Ignore the sign bit, do 2's complement on remaining part. then, we get our answer
thanks!
no we don't do 2's complement in second case, thats just to check our answer
Im pretty sure Ex2 is wrong.
Using the 2's complement representation, 0110 in binary is equivalent to +6 in decimal, while 1011 in binary is equivalent to -5.
So in deicmal number system, the task is to perform the following subtraction: +6 -(-5) = 11.
Task is performed as6+(2's comp(5))=-11
thank you, very concise and to the point.
Tq sir for this video I understood clearly your explanation is very good tq so much👍
1) 0010 (utilizes overflow discard)
2) 1001 (-7 because 2s comp = 0111 +7)
3) 0111 (utilizes overflow discard)
S M yeah I was always confused with questions like this one. if u left it as -7 or put it back to +7?? I just looked at the original question. 7 - 14 = -7, hence why I left it in its 2s complement form (1001)
Are you sure for 3) ?? 😬
3) and 2) is switched
@Anirudh I don't think so I have the same answer too
Saved my ass for the exam thanks! You may have an accent but you explain very well with good a good structure!
MK2EA if you're really concerned with his accent, I believe you have seen a strong accent. His speech is very clear for a non native speaker
1) 0010
2) 1001(2's complement of 7)
3) 00111
2nd answer in incorrect take 2's complement of 1001 because the sign bit is 0(5th bit)
0111
+ 0010 (2's complement of 1110)
---------------------
1001 ( now as there is no carry the result have to be converted in 2's complement form)
----------------------
hence the 2's complement of 1001 will be +7 i.e 0111.
for 3rd question could you explain me ...
@@achchhelalgupta3176 for 3rd ques answer is 00111
B is 01111
2's of B will be 10001
10110
+10001
------------
100111(final carry is one )
so neglect 1
answer will 00111
Its only 1001 or 10010
@@sandeepkumar7357 thank you , i was confused in 3rd question as i didn't add extra 0 for B at the MSB
thanks for providing knowledge to teachers
I had a doubt with another channel video but u cleared it thank you kal Mera exam hai🙃
Thanks for the great videos. Very informative.
When we get -5(right) in last qs. Then why are we doing 2s' complement again to get +5(that is wrong)?
Thank you so much! Amazing lecture!
when you use 2's comp. Expect an overflow.
At 5:42 you are mistaken,
If the sign bit is “0”, this means the number is positive in value. If the sign bit is “1”, then the number is negative in value.
yes correct man.
No that is the rule of 2s complement addition.. they're correct
Really an amazing way of explanation
U said the carry leads to overflow but u add a 4 bit number which doest fall into that range. Sir actually we are dealing with signed numbers so 1001 is a negtive number so we should not guess the number directly and take 2's complement . So 1001 is -7 and 1100 is -4 and subtrating them we will get -3 101 or 1101 right?
Sir I have a question, if A - B = A + (-B). Then what about A + B ? is it the same like the A -B formula ?
A - (-B)=A + B
@3:00 sir how come is the result positive if the carry is 1? .. That has to be negative then no? Please explain
this is exclusive for two's compliment method. Not taken in general .
You are amazing........
❤
Fillnaly ❤❤❤❤ thanks sir I searched whole day
Always the one stop solution 👍
neso academy is the best
i) 0010
ii) 1001 and (1001)2= -7
iii) 0111
Last one should be in 5bit
3.10111
3) 00111
1.0010
2.0111
3.01001
My last ans is coming out to be (00111)₂
1. 0010
2. -0111
3. 0111
mrs 3rd one is wrong
1. ans = 0010 2. ans = 2's complement of 1001 is 0111 3.ans 00111
3 rd is wrong
and 2nd also
Thank you sir helping me this subject
thank you very much for the amazing video. you are the best
Thank you sir
sir aapne last video m kha tha 1's comp. of A is -A and now in this video 2's comp. of A is -A......but 1's and 2's comp. of 6 is not equal explain......
Same doubt... How is it possible?
You are a savior
thank you neso
Sir, in previous (last) video you have said that 1's complement was negative form of number but in this you were saying that 2's complement was negative form of a number....
So which one is correct....
Thank you so much.
u said in previous lectures that....1 in signed bit indicates negative number....but here u consideres 1 as signed bit represents positive...how ...can any one make me clear??
yeah, Actually in four-bit binary we decide by MSB if MSB is 1 then its negative number but here we are deciding whether it is positive or negative by overflow, which is a different thing, I think now you can understand the difference between both
Mahipal Bishnoi ...then can we cal this MSB position also as signed bit??
Vasu Deva Rao no you can't call , this theory is different, if you subtract( 13 )- (4) you will get (11001) in this you can see answer is 9 and overflow and msb is 1 .but being msb 1 you can't call this negative in this theory ;)
Using 2's complement (0110)2 -(0100)2 =0010 and (0111)2 -(1110) =1001
nice video it really helped me out
is the final answer when there is no overflow after taking 2's comp or withtout taking 2's comp ?
Ans:- (1) 0010 or 2 in decimal (2) 0111 or (-7 ) in decimal (3) 111 or 7 in decimal
2nd ans wld be 1001
@@sahilprasantachoudhury911 exactly how do these wrong answers get all these likes XD
@@sahilprasantachoudhury911 no it's should be 0111 only and here it represents -7
In 11:07, why 1101 is negative of five(0101),why not -(0101)? It would be the great pleasure to know the reason?
had the same doubt :/
1011 is negative of five(0101)
1's complement of 5 (0101) is (1010) and the 2's complement of 5 (0101) is (1010) + 1= (1011)
Subtrsction (5 and 5) by 2's compelement.
so in the second example do i express my answer in 2's complement form or live it as it is??
Sir when I substracted
-48-23
(-48)+(-23)=-71
11010000 is 2's com.. of 48
11101001 is 2's complement of 23
Adding both we get
1 10111001 so we got carry 1 and is case of overflow and I neglected 1 the answer should be 10111001 which is not equivalent to -71
You said we need to take 2's complement of result when we don't get carry. If we get carry we simply ignore it and that is the answer but here even after neglecting Carry we don't get the answer please help sir I request you
Did you get the answer from any other source plz reply
I am having same type of doubt ...
Like -8-4 =-12. On performing 2's complement I am getting a carry and if I ignore the carry the ans which I am getting is not the correct ans... So pls if you both get the solution of this problem then pls give a reply
how we can solve 3rd question sir, result will come 5 bit or in 4bit
Hello Sir! i have a doubt in example no. 2 where you got the answer without a carry and again you are performing 2's complement. why is that?
Anas Khan The result which was obtained was negative and in its 2's complement form. So, to know the magnitude of the result (in this case +5), you have to perform the 2's complement of it(here -5).
Let me make your lives' easier:
Subtraction with Complements
The direct method of subtraction taught in elementary schools uses the borrow concept. In this method, we borrow a 1 from a higher significant position when the minuend digit is smaller than the subtrahend digit. The method works well when people perform sub- traction with paper and pencil. However, when subtraction is implemented with digital hardware, the method is less efficient than the method that uses complements.
The subtraction of two n‐digit unsigned numbers M - N in base r can be done as follows:
1. Add the minuend M to the r’s complement of the subtrahend N. Mathematically, M+(r^n -N)=M-N+r^n.
If M > or = N, the sum will produce an end carry r^n, which can be discarded; what is left is the result M - N.
If M
0 sign bit indicates a positive number and 1 indicates negative
so if i want to get the negative of a number should i only do the 1's comp and thats it or add 1 :3 im a little bit confusesd
My suggestion is to forget about one's complement arithmetic. Yes, it is sometimes used, but two's complement is FAR more common.
To get the two's complement of a number, change all the 1's to 0's, change all the 0's to 1's, and then add 1. You must always add the 1. This works for both positive and negative integers.
Thank you dude
Sir, I am still confused with overflow. Based on your condition for overflow, the example 1 will be indicated no overflow, since x'y'z+xyz'=1'0'0+100'=010+101=0 no overflow, but in your first example, you said it was overflow. Are we supposed to consider the discarded "1" as the sign of result? even though, the discarded "1" is considered as the sign bit of result, it will be like this: 1'0'1+101'=011+100=0+0=0. it is still 0, which is no overflow in terms of your condition for overflow.
It's actually, x-sign bit of A
y- sign bit of (-B)
if 1's compliment means negative of a number then how can 2's compliment also be negative of the number ?? please explain.
Thank you 😊 sir
Dear Neso Academy, i dont understand what is need of subtraction via 2's comp. when we can subtraction via 1's comp.. pls have a look on my querry
Because of 'end around carry'.
Neso said that it's easier to subtract using two's rather than one's
thank you very much
sir you can use shortcut method for finding 2s complement
I'm starting ❤️ with you now 😁
Thank You SIr
sir you said with binary number like 1011, etc. But how to do with numbers like (1011.10)2 - (110.10)2 ??
I don’t understand that for the sign bit of 1 is positive and 0 is negative. To my mind, it’s should be the opposite. Would anyone help clarify this situation please???
so for example 2, I got the same answer when I subtracted 1 and THEN took the 1's compliment of the result. Is this okay to do or did it just work out in this example? Thanks
8-bit 2s complement binary numbers: 121 - 67 ? Is it overflow? It seems I got an answer 11111111 with discarding 11
.Did you have to ignore any carry bits?
Is binary subtraction valid for only same bit number or even can I subtract different bit number??
If carry is 1 out put should be negative right
Thank youu so much
What about Binary subtraction using 2s complement which have fractional part too?
Getting into binary fractions is way beyond the scope of the video.
Thank you...
What if u have been given 8 bit binary numbers to add using twos complement how do u neglect final carry?
12:12 the answers are -----------------------
1) 0010
2) 0110 (-ve)
3) 00111
how the second answer is solved plz explain in detail sir
🔴 H/W Problem 1:
✔️ ans: (0110)₂ - (0100)₂ = (0010)₂
...............................................................
🔴 H/W Problem 2:
✔️ ans: (0111)₂ - (1110)₂ = (-0111)₂
...............................................................
🔴 H/W Problem 3:
✔️ ans: (10110)₂ - (1111)₂ = (00111)₂
...............................................................
You say 0101 = 5 in decimal. And that the 2s compliment of 0101 (5) is 1011.
But I'm confused, doesn't 1011 = 11? Why do you say it equals negative 5?
I'm not very experienced with the theory behind the subject but I'm pretty sure it has to do with the fact that when we use 2's complement we split the number of possible combinations into two sides, one side for the positives and one for the negatives. If you imagine it as a circle where 0000 = 0, 0001=1 and so on then if we travel in the opposite direction of the circle we travel along our negative side, IE from 0000 if we go left we get 1111 which is equal to -1 and from there 1110 will be equal to -2 etc.
pherricoxide.files.wordpress.com/2008/09/binary_circle2.jpg
You are confusing 2s complement with unsigned numbers. A combination of bits may have different meanings in different number systems (unsigned vs 2s complement) the same way a combination of letters may have different meanings in different languages. A number in 2s complement has two parts, a sign bit and the number itself. It is true that 1011=11 if you were discussing unsigned binary numbers, but for 2s complement recall that the leftmost bit is the sign, so the leading 1 is actually a negative sign and not a number at all.
@@seangeary8937 so should i write beside the number it's 2's complement to let the others know there is a sign bit
Will overflow happen if I'm adding (100)10 and (-46)10 ?
How (-B) becomes 0101 in the 2nd problem. If the MSB is 0 then how it becomes negative number. Kindly explain.
yeh example 2 mai 1011 final answer hai ya 0101
well done NESO...I have a question and will appreciate if anyone answer it...
to perform -7-3 we will do (-7)+(-3)
7 in Binary = 0111 in 2's complement it is -7 = 1 0 0 1
3 in Binary = 0011 in 2's complement it is -3 = + 1 1 0 1
________
1 0 1 1 0
NOW WE GET A FINAL CARRY THAT IS 1 THE ANSWER SHOULD BE RIGHT AND IN ITS TRUE FORM..IT SHOULD GIVE US 1010 THAT IS 10....but it is not giving us right ans...help will be much appreciated
I know we get 1010 we get do the 2's complement of 0110...but my confusion is how to know that we need to convert back the ans...in the first example....you didnt convert the answer...in second you did..why we need to convert our ans in my case when we have final carry = 1
When we need to convert our answer back into 2's comp...in your step 3 you said if we get a F.C = 1 we dont need to change answer as it is in true form...but when we do -7-3 we get a F.C...and we need to convert it back in order to cross check
that is why i am asking...i need to cross check to get full marks..9-4 = 5 = 0101 that is correct....
but -7-3 = 0110.....how come we know that answer is correct...??when we convert our answer only if we get F.C = 0.
i dont understand a point. In this video you said that the 2 compliment of a number is his negative. But in the previous video, you said the same thing with 1 compliment! So what is the difference???
thank you
1. 1 0010(+2)
2. 0 0111(-7)
3. 1 00111(+7)
Same
If we have 5 and 4 bit no. How we know carry is generated or not.
1) 0010 (+ve true form )
2) 1001( -ve 2's comp form )
3) 10111( +ve true form)
Is there anyone who can make mr understand the condition for overflow with a example i can't understand the thing...🙂🙃 9:17 9:17
How to do -2-6...the answer I get is 1000 with carry 1 . But 1 carry signifies + ...but the answer is -
Did you got the answer from any other source please help me
What about - 1-2. There is a carry generated yet it isva negative number
1-0010 +ve
2-1001 -ve
3-00111 +ve
your last one is not correct
it's 10111
@@oggy107 thanks i will see this
please , what is the minimum number of bits to represent 0 in 1's complement and 2's complement
I believe 1 bit, the result would be 0 or 1 for 1's complement, and 0 for 2's complement.
Sir i am aktu btech first year student and i solved another questions through this method but my professor told me that this is not right way to solve plz guide me from where I need to learn the method which supports the concept of Fellercher standard book plz 🙏🙏🙏🙏🙏🙏🙏 if anyone now about this plz guide me
1:0010
2:0111
3:01001