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Fast Math Tricks - How to multiply ANY 2 digit numbers up to 100 - the fast way!
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- เผยแพร่เมื่อ 12 พ.ย. 2019
- #fastmathtricks
#mentalmath
#mathtrick How to multiply ANY 2 digit numbers numbers up to 100 - calculating the fast way!
Using this method you will be able to multiply any pair of two digit numbers with each other - faster than a calculator! Become a math genius in no time at all using vedic math!
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Learned something new today. Can't wait to show my daughter. Thank you!
>:)))))
It's called as Vedic Math.. Indian legacy... u can search for same.. and u will find more content
Is this the "Foil Systems" like in algebra one?
My son LOVES math but sometimes struggles with the way it’s taught in the American classroom. I am so glad that we as parents can now find resources at our fingertips that help our kids feel confident in their abilities… and excited that they learned it in a new way 😊
The amusing thing about this trick is that this is what we learned in elementary school when learning to multiply. This is just a simpler way of thinking about it that doesn’t really explain how it works but gets the job done.
Yep. And both this method and the standard method are really just the distributive law: (x+a)(y+b) = xy + xb + ay + ab. In the U.S., students call this rule "FOIL," but it's really just the distributive law three times.
The dislikes are from the people that try to race a calculator
True there haters this actually helped me
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As mentioned in other videos, if you generalise this using algebra, it makes perfect sense.
A two-digit number with digits ab would be expressed as (10a+b).
If you multiply (10a+b) with another two-digit number (10c+d), you will get (10a+b)(10c+d) = 100ac + 10ad + 10bc + bd
You can then factor this as 100(ad) + 10(ad + bc) + 1(bd)
Therefore, you multiply the units (b and d) to get the units digit of the answer
You multiply the first digit of one number with the second digit of the other number (a and d), and vice versa (b and c), then add together to get the 10s digit of the answer
Then you multiply the 10s digit of both numbers (a and c) to get the 100s digit of the answer
But what if you wanted to multiply _3_ 2-digit numbers together, such as 54 x 26 x 38, for example?
Well, this would be (10a+b)(10c+d)(10f+g) - I'm deliberately avoiding the use of 'e' for obvious reasons (i.e. Euler's number).
If we expand this out, we get 1000acf + 100acg + 100 adf + 10 adg + 10 bcg + 100bcf + 10bcg + 10bdf + bdg
If we factor this, we can get: 1000(acf) + 100(acg + adf + bcf) + 10(adg + bcg + bdf) + 1(bdg)
We can then see the following:
To get the units digits, we have to multiply the units digits of each of the answers (4 x 6 x 8 = 192 - we then write 2, and carry the 19)
To get the 10s units, we need to multiply the units digit of two numbers, with the 10s digit of the remaining number.
This should be done three times, each time changing which number we take the 10s digits and units digits from:
4 x 6 x 3 = 72
4 x 2 x 8 = 64
5 x 6 x 8 = 240
We then add these together, 72 + 64 + 240 = 376
We then add the 19 we carried over previously, to get 395.
We then put the 5 in the 10s digit, and carry the 39.
For the 100s digit, this is achieved similarly to the 10s digit, except we multiply one units digit from each number, with the 10s digit of the remaining two numbers:
4 x 2 x 3 = 24
5 x 6 x 3 = 90
5 x 2 x 8 = 80
Add these together to get 194
We then add the 39 we carried over, to get 233
We then write the 3 in the for the 100s digit, and carry the 23.
Finally, for the 1000s digit, we simply multiply all 3 10s digits together:
5 x 2 x 3 = 30
We then add the 23 we carried, to get 53.
We should therefore, have the answer 53352.
In summary, if we simply express the 3-numbers as AB x CD x FG and the result as HIJK:
H = ACF
I = (BCF + ADF + ACG)
J = (ADG + BCG + BDF)
K = BDG
And, just for the sake of it, what about a 2-digit multiplied by a 3-digit number?
I shall cut out the general algebraic method and go straight to it - let's use 234 x 56 for example
The units digit of the answer is the product of the units digits of the two numbers (4 x 6 = 24) - the 4 is the units digit, and we carry the 2
For the 10s digit:
Multiply the 10s digit of the 3-digit number, with the units digit of the 2-digit number (3 x 6 = 18)
Multiply the 10s digit of the 2-digit number, with the units digit of the 3-digit number (4 x 5 = 20)
Add these to get the answer 38 + 2 (carried over from the units) = 40 - digit is 0, then we carry the 4
For the 100s digit:
Multiply the 100s digit of the 3-digit number, with the units digit of the 2-digit number (2 x 6 = 12)
Multiply the 10s digit of both numbers (3 x 5 = 15)
Add these to get the answer 27 + 4 from the 10s digit = 31 - the units is 1, and we carry the 3
The 1000s digit is the product of the 100s digit of the 3-digit number, and the 10s digit of the 2-digit number) (2 x 5 = 10)
Adding the 3 we carried, we get 13
This gives us the answer 13104
In summary, for ABC x EF = GHIJ (these represent _digits_ not variables, i.e. ABC is a 3-digit number with the digits A B and C, _not_ a product of A x B x C)
G = AE
H = AF + BE
I = BF + CE
J = CF
Algebruh
Mathematical Waffle
That is a lot of typing sir/maam
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You are a wonderful teacher who helped me in the way I delivered my lesson in front of the third grade without hesitation and fear with my head held high. I wish you a lot of happiness, appreciation and respect.
Before I didn’t even know how to do this method. And then I watched this video. Straight away, i got all the questions right and it takes 2 seconds!! THANK YOU
Thank you. I'm glad you liked it.
The fastest way to multiply in your head is to:
Lets say you have 12 x 52
Take the smallest/easiest number you can use to multiply with, which in this case, its 12.
Now multiply 12 by the first digit (12 x 2 = 24), and remember that.
Multiply 12 by the second digit now (12 x 5 = 60). Since it's in the TENs place, you add a zero to the end of that number. (60 becomes 600).
Now add those two answers together (24 + 600 = 624)
(It may seem like a long way to do it, but I just wanted to explain every step clearly, making it seem long to do)
(Also, sadly it doesnt work half the time. If you have something like 86 x 53, then you would have to do a lot more steps that I'm not bothered to explain. And you would probably either need a sheet to write one or two numbers down if it's a sum like 86 x 53)
Just Jum tenths would be for example 56.7 the 7 is in the tenths. What I think you mean, is tens. Otherwise, this method is great!
Thanks for this, you always upload things I need the day I have a test.
Edit: I’m not being sarcastic
That accent makes the video even better!
It's a lot harder to keep track of all the numbers in the last problem without using paper to write it down on, unlike the square root trick, lol. It took me quite a while to get the answer only using mental math (only for the last example, anyway), but then again, I am dyslexic... despite math being one of my strong suits (as well as spelling, go figure LOL). Very informative, I wish that teachers would use these kind of examples as it makes learning a lot more fun, which studies indicate strongly that students will not only have an easier time learning, but also retaining the information. Just like I still remember the old PEMDAS from the acronym used when you're given a problem with multiple equations being done in a single problem, as far as which parts of the solution are found first. (Paranthesis, Exponents, Multiplication, Division, Addition, Subtraction). I'm sure that most people here who have taken algebra still remember, "Please excuse my dear aunt Sally".
Cool man
I really wish they taught us this in primary school. this would have helped me so much. I’m so upset i’m only finding this channel now!
THIS WILL HELP ME A LOT ON SOLVING THE PERCENTAGE!!!!! Thank you soo much!!!!!! I wish i knew this before!!!!
Thanks for helping my son, he become master please keep on teaching my son is a great fan of you. God bless you
amazing video. I love how you explain it so clearly
This is brilliant! I'm very grateful for this (and I like your handwriting) :)
Cant believe I'm only just finding this! This is gonna help so much in my upcoming exam :D Thank youuuu
Hope ur exam went ok👍
The best math channel
Great video tecmath!
Thank you so much for this super easy technique. Memorise the 'rainbow trick' and you are set to go...
Great trick.. thanks for sharing it. Although I use a calculator every day in my work, I like to do as much math as possible in my head. Feels good when the calculator verifies it. Thanks for all the good teaching and learning that goes on at your channel. Thumbs up!
Absolutely awesome! Brilliant for any kind of maths related aptitude tests. Any chance for divison next please?
I don’t have kids but my nephews will be appreciating this method
I am using this for years this is amazing everyone 🎉
Mate, do you do any one on one tutoring? Im based in Sydney, and need some help getting ready for a military pilot test Ive got coming up, and really want to nail the mental maths sides of things. Would be awesome if you could help!
Very useful math trick
Thank you so much
Yes i did get the answer thank you so much learned something new today!... keep it up.
Learned something newww todayy!! Thank u so much for your wonderful videoss! Can’t wait to share it with my lil siblings!!!
Also when timesing double digits with 13
26x13
2_6
2+6=
286
26x13=286
ok this is for the people that get like 12 thousand or what ever , you carry over your digits. so lets say 36 x 24 , 4 x 6 thats 24 put a 4 in the units and keep that 2. then times 3 by 4 you get 12 and and 6 x 2 you get 12 add them togther you get 26, keep the two, then 3 x 2 which is 6 add the two you got and you have 8 then put that in it and you have 864. hope i helped
Like magic and really easy to do on the fly!
10/10
thank you tecmath
A fantastic way of explanation
I knew it there was something missing in the first video related to this one. Until I figured out you will need to carry the "tens digit" if ever you acquired a 2-digit number result for the right side.
Thank u sooooooooo much I have a math test tomorrow and I realised that I can't do two digit multiplication and this helped me so much
Thanks a lot it really helped me since I’m Aussie and my teachers want me to do it a specific way! Hope you have a great day.
Thanks tecmath. Mes élèves ont bien aimé cette technique pour le calcul mental
Thanks really helped me
This is great! A whole new way to look at math! Thank you!
I JUST LOVE YOUR MATH TRICKS
I don't know why people unlike the video this is easy and simple thx to you tec
I love your channel, it's very very helpful! These are very genius tricks!
thank you so much!
hi! i got confused when i tried this set of numbers, how would you solve 89 x 77 using this method?
First 7 times 9, 63. You carry the 6. Then add 8*7 and 9*7 = 56+63=119. Pull the 6 down, and you get 125. Then carry the 12, and do 8*7=56, and add the 12; 68. Then the answer is 6853. Very confusing, I know.
Thanks for the math tricks, really helpful
I like it..😁 because I suck at math, but now.. I feel like I'm a part of the Math Club. Thank you. .
Nicely explain .. common rule for any 2 digit number .. that is nice
Wow. Just wow. Thanks mate!
Good videos. You should create a mental math app
Thank you for sharing this technique☺️
tecmath, what program do you sue for these videos?
Momo Mamo Any drawing program like Microsoft Paint will work.
Thanks a ton.....this video is really helpful.👍
How did I not know this? I have tried to figure it out on my own but never got it. I must not be very _____. All I can say is Thank YOU.
The blank says smart
I loved this trick, It's really fast and understandable.
As always, thanks for this tricks
Have job exams coming up, found you just in time. Great lessons, big thanks from India
Thank you sir
Why don't they teach us in school? You made my life much easier cause I am kinda slow in calculations like this, but this helped me a lot. I can't wait to learn more!
Best explanation
This reminds me of foil method for multiplying things like (x+4)(x+2). Pretty neat
It's a great help to do my maths test easily thank you 🙏
Best teacher
You saved my life ❤️
Thats great i have never seen these kind of easi tricks before. Even i am graduated
Great as usual!
You are gonna help me look like a math genius to my kids. Cheers mate 👍
Why its not applicable to 79×75
What is the best way to present this lesson?
wonderful video
thanks, tecmath this was really helpfull to me :D
thank you i feel like i will do better in solving my math problems thank you
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Thanks
Why not left to right?
Thank you so much sir🙏🏻
You helped me a lot ❤️
great video!!!!!!!!!!!!
Thank You so much
you are amazing! You are like Faci of math.
Fantastic thank you
bloody love this. I feel like Einstein now. Thank you very, very much mate.
Would u pls show how i have to follow for mutiplying 6549x8378.its a little bit different .pls show step by step.thnks
Thank u so much I have time table tomorrow and I think I will get 100/100 tysm . Oh help pretty much
This reminds me of the video where he did 3 by 3 multiplication.
So nice and easy method
If take electronic deice why it get destry when hooly water poryued on
First. Love these videos. Very helpful
SOOOO much easier than American/US taught math.
Hello, you are a very good teacher your videos helped me a lot, could you please make a video about trigonometric equations
I have a closely related question regarding long multiplication. If only the hundreds and thousands columns need to be correct, can the routine be multiplied by just adding overflows and not actually storing tens and units. When the grade-school method is used, the final add is thus:
DC
AB
---------
So the units (B) value cannot overflow during add since nothing is added and likewise, the hundreds column ONLY needs to carry the tens column, it doesn't need to be stored.
I do appreciate that it is a very unusual question but it is of great practical utility. I have looked at both your low to high & high to low orders of multiplication but I'm still using pencil and paper.
Many thanks.
It’s more about memorising the method. Once you’ve done that you’re sound.
I wish you your head always held high, this phrase means in Palestine that you are a hero in the work you are doing
Where have you been all my life I bro
Very helpful
Genius work
Amazing
Just same multiplication method. Just not having them top and bottom to do the calculations.
he himself cant believed he solved it.
Thanku sir 😇
u r a literal god
sir...please upload few division tricks in order to do division as fast as possible. thankyou
I loved it thanx a lot friend now people will think im a genious
you can’t spell genius right
@@lrthy sry friend for mispelling im not an englishman .
oh my bad יעקב לוי