"axiomatic", "corollarily": Yes, he has had that kind of maths lectures. "That's not too difficult to proove, I'll leave this as an exercise to the viewer.": Now he is just messing with us traumatised ones xD
For those of you still traumatised. 15 is odd. You have a choice in every row of having 2 odds and an even or two evens and an odd. You have to choose 2 evens and an odd to make the result odd. You could try one row with 3 odds but this forces 2 odds and an even onto the diagonals which doesn't work. Hope this helps, there may be a more elegant explanation.
@@PauxloE That's why I wrote "messing with us", he only said this after explaining it many, many times in detail. The phrase, though, does remind me of some of my professors while Simon definitely does not remind me of those. And I doubt that Simon would use the phrase in a non-joking manner in a video.
TheSolarFuture Enthusiast A proof left “as an exercise for the reader” is very often one that the writer can’t be bothered to write out. Usually, this means one of two things: either it’s extremely trivial, or it’s incredibly complicated.
In case anyone is curious - since every row/column/diagonal adds to 15, it must contain one odd and two even numbers. This is because two odds always add to an even, so two odds + an even would be even. The only way every row, column, and diagonal can have two even numbers is by putting all the evens in the corners.
My favourite, a guitar intro! And I love the new artwork, I wish I was talented enough to draw people. More beautiful logic from Aad, this is perfect end to a hot and stressful day
19:04 "Now actually there's a few ways we can resolve this..." - proceeds to list two clever reasons while ignoring the plainly axiomatic one (already a 9 on the rising diag) (I'm glad I'm not the only one who does this, far too often I'll solve something the hard way before noticing the much easier way staring me in the face)
What another superb puzzle from Maestro Aad van de Wetering! That was a couple of very enjoyable head-scratching hours, followed by watching expert solver Simon knock it off in under a quarter of the time. Thank you to both creator and solver!
Solved it in 48 minutes on my second try. My first went a bit catastrophically but I'm happy I managed to solve it on the second one. I also ended up looking up a list of prime numbers, because figuring the options out myself would have meant more stress than I wanted to bother with today 😅
I spent literally 4 hours today doing a medium samurai sudoku from the paper and it used up all my thinking power for the day, I am slowly getting better and implementing some strategies that ive been learning from cracking the cryptic but still have a long way to go x needless to say i won't be attempting this one I'll just enjoy watching you complete it Simon 😊
I think they adressed that request some time ago, saying that they're not very technically versed so they wouldn't know how to set it up and that they'd also think it might be boring. At least that's the response I remember, might be slightly off
Does anyone else think Simon would make a good teacher? No matter how many times he has explained something in other videos, he always seems to explain it like it's the first time.
I didn't solve this one without help from the video, but I did see something clever that wasn't mentioned. For placing the 5's on the diagonals, when 5 had four options in box 9, I noticed that both R2C2 and R8C8 could see both places on the other diagonal where the 5 could be (R2C8 and R8C2), so neither of them could be a 5. That limited the 5 in box 9 to column 9, which placed the 5 in box 6 and forced it off the diagonal in box 3. Then it had to be on the diagonal in box 7, which helped place the 5's in boxes 1 and 9.
Also, when you have spotted the two available positions on the / diagonal eliminate two positions on the \ diagonal, there's only one position available on the \ diagonal, in column 9. So you can place the 5 in box 9 straightaway.
@@reikoyukawa4873 Almost what you said. 😀 Only you had an extra step, limiting 5 to column 9 in box 9 initially, then using that to place 5 in box 6, then box 7. Only then did you say it allowed you to place the 5 in boxes 1 and 9. ("Then it had to be on the diagonal in box 7, which helped place the 5's in boxes 1 and 9") I was just being penickity. When you said it restricted 5 to column 9 in box 9, if you looked at the diagonal, then it allowed you to place the 5 directly in box 9. Same result.
I immensely enjoyed the part where simon in the 13th minute showed the 79 pair could only take a 9. The level of satisfaction would be something else if one were do it on one's own. There is always hope for the future.
@@hangugeohaksaeng yeah it depends how you see it. But at least it's some kind of pseudo prime, maybe even the first one to help create the first RSA algorithm
hangugeohaksaeng as someone who’s memorized if the first however-many numbers are prime just due to constant usage, i was hoping he’d immediately catch on that
@@MrCheeze Yeah he did somewhat underutilize the prime condition at points, I was expecting him to pencil "39" next to the initial 5 right away, he got to it soon enough by eliminating composites but could have had it immediately (That said he got through all the prime clues quickly enough that it didn't really matter much)
46:53 Urgh... this was very tricky to solve, but luckily not impossible. Well done Aad, another awesome work! And Simon please play that guitar more often for us!
Love the guitar intro! That was wicked start to the puzzle that completely stumped me, but I was able to take it from there (though it took me much longer). I had the same very satisfying finish on those 68 pairs. Amusingly I happened to know immediately that 91 isn't prime because of American Football. Thanks to Tecmo Bowl I've never had any trouble spotting multiples of 7!
All I can say is NICE PUZZLE! This one was tough. I made a mistake to begin with that seemed good until 20 minutes later I came to have clashing digits. Restarted and with your help noting that the 5 was the central digit (somehow I had placed it in the top right the first time :p ) the puzzle was relatively easy to fill in using mostly the same steps you did in a slightly different order. Still took me over an hour to finish. I have to get quicker at spotting the logic. Practice practice practice. :) Thanks for the video!
So proud of myself for solving this one unaided, and it only took me just under 2.5 hours. Then I come back to the TH-cam channel and watch Simon solve it better than I did, and in something like five minutes...
There was one part where Simon explains why a 9 could not be in the upper right corner in the center box using 2 processes of elimination. There was a 3rd elimination in that a 9 was in box 7 on the diagonal line and thus the 9 could not repeat on that line.
Simon is much more experienced in sudoku than me, but I seem to be more experienced with primes. I was yelling (internally) about combinations that cannot be prime throughout the video.
The central cell is the only place a 3 can go in the box. The 3,7 pair in box 4 rule it out from the top row. The 3 in box 7 rules it out from the bottom row by normal Sudoku and from r5c6 by king's move.
It's really impressive how tight the logic is at the beginning; my logic was slightly different (I realised the only prime number to begin with a 7 was a 9, so 7-9 had to be together somewhere in the magic square), but the steps were nearly exactly the same!
46:08 Really thought I'd have a better time, but I struggled mightily on the opening part of the puzzle (resigning myself to a couple bifurcations) before finishing strong.
91 is interesting as the only non prime number less than 100 that doesn't have an easy check for being not prime. If a number is divisible by 2, 4, 6, 8, 10 or 12 it's obvious that it's not prime because it's even. If a number is divisible by 3 or 9 you can sum the digits and see if that sum is divisible by 3. If a number is divisible by 5 it's easy to check that it's not prime (it ends in 5 or 0). 7 could cause issue, but 7x7 is square and pretty obvious. Then the only option left is 7x13 = 91. Anything else is over 100 (7x14 or 13x8 are over 100). Therefore 91 is the composite number less than 100 that's mistaken for being prime more than and other number less than 100.
"If a number is divisible by 2, 4, 6, 8, 10 or 12..." What's so special about the even numbers up to 12? Simpler to say "if a number is even then it's divisible by 2, so not a prime"?
it really was lovely, the addition of the primes and the offset magic square was a nice change. Simon it was interesting that there were several times where you wouldn't scan both legs of the Central × before you started following subsequent clues... is the fact that I did a deficiency on my part? how do you prioritize which clues you follow vs which ones you save for later?
I had a go and managed to work out that the 2 had to go in the top left cell, but then messed up the prime. I think I got confused with the combination of the magic square and primes and ruled out candidates that I shouldn’t have.
May I suggest you put the instructions on the puzzle page? I keep having to flip back to the paused video if I want to clarify an instruction, and it also makes it hard to share the link with someone.
I got quite frustrated with this one. I figured out the magic square and got about half way through the whole puzzle... then got totally stuck about half way through. I guess I missed one of the numbers that was eliminated on diagonals but oh well. win some lose some lol great video
For someone who memorized the list of primes below 100, seeing that 9 in the 2nd box and not the 7 right after it is agonizing. There’s only one prime number in the 90s and that’s 97. 91 is divisible by 7 and 13.
It's because R1C2 doesn't see R4C1, so it's possible that both of them are 9... If you forgot that 9 now can't appear in the magic square twice, which I forgot until just now, and I bet Simon forgot that in the moment
I still don't see how he removed the 9 from r4c2. Without that he can't proceed the way he did. Since he found the 9 in the magic square, then that would remove the 9 in r4c1, not r4c2. Help me see..., please, because I be cornfused.
NM, I went back and reviewed it. I get it now! the 9 was removed due to the possibles for 9 in box 1. Either one would preclude a nine in r4c2, one via sudoku rules and the other via kings move restraint.
Believe in yourself! I recommend trying to solve it, and using the video if you get stuck. This is one of the simpler Aad puzzles not requiring advanced techniques
Just when I think Simon can’t get more talented.
He goes and makes THAT intro...
Wes Ley I didn’t say he created it 🤦♂️
Having two top level sudoku solvers being drawn as GTA characters wasn't something I ever expected to see.
Just imagine the missions they give you: The first 40 minutes is just figuring out who exactly is it you're supposed to kill.
The joy when Simon said : I've got it!
“Now maybe we do some sudoku; boo, hiss”
I love when Simon plays guitar for us in the intro instead of the normal song
2:20 - Rules
5:26 - Let's Get Cracking
"axiomatic", "corollarily": Yes, he has had that kind of maths lectures. "That's not too difficult to proove, I'll leave this as an exercise to the viewer.": Now he is just messing with us traumatised ones xD
For those of you still traumatised.
15 is odd.
You have a choice in every row of having 2 odds and an even or two evens and an odd.
You have to choose 2 evens and an odd to make the result odd.
You could try one row with 3 odds but this forces 2 odds and an even onto the diagonals which doesn't work.
Hope this helps, there may be a more elegant explanation.
@@thesolarfutureenthusiast1102 That's a neat way to put it.
Or just watch older magic square videos on this channel, I remember it being demonstrated already.
@@PauxloE That's why I wrote "messing with us", he only said this after explaining it many, many times in detail. The phrase, though, does remind me of some of my professors while Simon definitely does not remind me of those. And I doubt that Simon would use the phrase in a non-joking manner in a video.
TheSolarFuture Enthusiast
A proof left “as an exercise for the reader” is very often one that the writer can’t be bothered to write out. Usually, this means one of two things: either it’s extremely trivial, or it’s incredibly complicated.
18:33 "Now maybe we do some sudoku! Boo, hiss. :)" That legit made me laugh out loud wow
I believe the correct term is "mathemagic".
I'll leave that as an exercise to the viewer - I legit screamed. Any Maths students here got major "the proof is simple and left to the reader" vibes?
I do not even know why the viewer would do the exercise. It is intuitively obvious to casual observer.
I’m not going to be that harsh, Joe... lol
but Simon explains the magic square in several video. And by now I’d be done explaining it too.
In case anyone is curious - since every row/column/diagonal adds to 15, it must contain one odd and two even numbers. This is because two odds always add to an even, so two odds + an even would be even. The only way every row, column, and diagonal can have two even numbers is by putting all the evens in the corners.
I like the new intro. The guitar is a nice touch and the drawings of Simon and Mark are fantastic!
i think this is the first video i’ve seen where simon really does trust his pencil marks 👏🏻👏🏻
I'm lost for words. These setups with Aad just get better and better
Guitar playing and graphic heads in one video, and they were both BEAUTIFUL!
The artwork and intro music was the best part of this video!
14:59 Was anyone else shouting “neither is 91 because it divides by 7!”?
91 doesn't divide by seven factorial?
It's not as obvious as a multiple of 3, but it would have given him that digit. But yeah... I also noticed 13*7=91 at 15:00
Cadde Ha! ;)
No, I was just thinking it, and as a multiple of 13 rather than 7...
I just happen to know that the numbers from 90 to 97 are special because they are the first that have only one prime: 97.
My favourite, a guitar intro! And I love the new artwork, I wish I was talented enough to draw people. More beautiful logic from Aad, this is perfect end to a hot and stressful day
19:04 "Now actually there's a few ways we can resolve this..." - proceeds to list two clever reasons while ignoring the plainly axiomatic one (already a 9 on the rising diag)
(I'm glad I'm not the only one who does this, far too often I'll solve something the hard way before noticing the much easier way staring me in the face)
I've said it before: Aad and Phistomafel are my favorite setters to watch, and this is no exception! Always a treat when we get one of them :)
What another superb puzzle from Maestro Aad van de Wetering! That was a couple of very enjoyable head-scratching hours, followed by watching expert solver Simon knock it off in under a quarter of the time. Thank you to both creator and solver!
I'd been feeling super stressed today, but the guitar music immediatly calmed me down and made me smile. Thank you.
Solved it in 48 minutes on my second try. My first went a bit catastrophically but I'm happy I managed to solve it on the second one. I also ended up looking up a list of prime numbers, because figuring the options out myself would have meant more stress than I wanted to bother with today 😅
@@evah4431 It took me 49 minutes in my second try as well. Box 1 broke after 15 minutes in my first try when I couldn't put a 7 in it.
@@pedropedropedro7036 for me it was the 7 as well! But with box 5. That darn seven :)
Simon's *excited voice* when nearing the end of the puzzle...
makes me feel like I'm short of breath everytime lol
Great stuff Simon. I am a huge fan of Aad's puzzles
I spent literally 4 hours today doing a medium samurai sudoku from the paper and it used up all my thinking power for the day, I am slowly getting better and implementing some strategies that ive been learning from cracking the cryptic but still have a long way to go x needless to say i won't be attempting this one I'll just enjoy watching you complete it Simon 😊
0:11 that Simon image is MIGHTY
totally rad, love Street Spirit. fun intro for sure
This one was one of my favourite to solve. Kept on giving. Very nice
What an incredible solve! The logic in this one is unbelievable. Not a lot of people have their multiples of 13 readily available.
Really enjoyed the guitar and the cool new portraits at the start.
The puzzle was cool too I guess.
Yessssssss, Simon's got the Radiohead jam :)
Ever thought about getting an eye tracker? I think it would be very interesting to see just where you are looking as you are solving the puzzle.
I think they adressed that request some time ago, saying that they're not very technically versed so they wouldn't know how to set it up and that they'd also think it might be boring. At least that's the response I remember, might be slightly off
They talked about in their recent Q&A post on their community tab.
What a great feelgood channel! Lovely stuff, keep it coming!
Just when I thought these videos couldn’t get more chill and relaxing, Simon goes and plays Street Spirit. He should do some full covers.
"here's this picture of mark, looking like a... baddie..." I LOVE SIMON
Does anyone else think Simon would make a good teacher? No matter how many times he has explained something in other videos, he always seems to explain it like it's the first time.
I didn't solve this one without help from the video, but I did see something clever that wasn't mentioned. For placing the 5's on the diagonals, when 5 had four options in box 9, I noticed that both R2C2 and R8C8 could see both places on the other diagonal where the 5 could be (R2C8 and R8C2), so neither of them could be a 5. That limited the 5 in box 9 to column 9, which placed the 5 in box 6 and forced it off the diagonal in box 3. Then it had to be on the diagonal in box 7, which helped place the 5's in boxes 1 and 9.
Also, when you have spotted the two available positions on the / diagonal eliminate two positions on the \ diagonal, there's only one position available on the \ diagonal, in column 9. So you can place the 5 in box 9 straightaway.
@@RichSmith77 Right, that's what I said. Then once you place the 5 in box 9, you can get the 5's in boxes 1, 3, and 6.
@@reikoyukawa4873 Almost what you said. 😀
Only you had an extra step, limiting 5 to column 9 in box 9 initially, then using that to place 5 in box 6, then box 7. Only then did you say it allowed you to place the 5 in boxes 1 and 9. ("Then it had to be on the diagonal in box 7, which helped place the 5's in boxes 1 and 9")
I was just being penickity. When you said it restricted 5 to column 9 in box 9, if you looked at the diagonal, then it allowed you to place the 5 directly in box 9.
Same result.
I immensely enjoyed the part where simon in the 13th minute showed the 79 pair could only take a 9. The level of satisfaction would be something else if one were do it on one's own. There is always hope for the future.
29:00 "So we go six six eight eight ... check ..."
And what a missed opportunity to say "check ... mate" which would rhyme.
That is clever
Poor 91, everyone forgets that it's composite
Don't you mean lucky 91? It get to sneak into the exclusive prime club.
@@hangugeohaksaeng yeah it depends how you see it. But at least it's some kind of pseudo prime, maybe even the first one to help create the first RSA algorithm
Yeah, I was wondering if it would make a difference that he didn't have a prime list to reference, and it eventually did.
hangugeohaksaeng as someone who’s memorized if the first however-many numbers are prime just due to constant usage, i was hoping he’d immediately catch on that
@@MrCheeze Yeah he did somewhat underutilize the prime condition at points, I was expecting him to pencil "39" next to the initial 5 right away, he got to it soon enough by eliminating composites but could have had it immediately
(That said he got through all the prime clues quickly enough that it didn't really matter much)
I love the prime number rule. Made me remember my divisibility rules from grade school.
That was a fabulous puzzle with a fabulous solve.
46:53 Urgh... this was very tricky to solve, but luckily not impossible. Well done Aad, another awesome work!
And Simon please play that guitar more often for us!
Noticed the artwork at the start, thought it was new. Beautiful
I loved the prime number twist to this one!
Another great puzzle from Aad
Love the new intro! So pretty!
I love how Aad always seems to finish with a disambiguatable deadly pattern
I'd dearly like to know how you can design a sudoku so that such a sophisticated technique is needed at the *end*.
Great musical intro. More of that please
This was one of my favorites
Love the guitar intro! That was wicked start to the puzzle that completely stumped me, but I was able to take it from there (though it took me much longer). I had the same very satisfying finish on those 68 pairs. Amusingly I happened to know immediately that 91 isn't prime because of American Football. Thanks to Tecmo Bowl I've never had any trouble spotting multiples of 7!
I about had a heart attack when he was left with a deadly pair. Thank you king's move!
omfg are we going to talk about Simon playing Street Spirit BEAUTIFULLY?!
Solved it with help from the video. Starts easy, then becomes very hard.
Excellent song choice! For those who are curious,the intro song is Street Spirit (Fade Out) by Radiohead
Brilliant solve Simon! I'm absolutely loving this channel and it's content. Though, my favorite bit has to be the boo hiss. Lol.
Trying to figure out how you were able to jump to the '3' versus the '9' in the center square at 17:18 in the video
i believe it is because he saw the 3 7 pair to the left meaning the 3 had to be in the middle row
All I can say is NICE PUZZLE! This one was tough. I made a mistake to begin with that seemed good until 20 minutes later I came to have clashing digits. Restarted and with your help noting that the 5 was the central digit (somehow I had placed it in the top right the first time :p ) the puzzle was relatively easy to fill in using mostly the same steps you did in a slightly different order. Still took me over an hour to finish. I have to get quicker at spotting the logic. Practice practice practice. :) Thanks for the video!
So proud of myself for solving this one unaided, and it only took me just under 2.5 hours. Then I come back to the TH-cam channel and watch Simon solve it better than I did, and in something like five minutes...
Love your solving skills, but I totally got lost after you solved the magic square. It gives me joy watching you solve hard sudoku 👍👍
Street Spirit is so meditative to play - a nice surprise at the start of this vid.
There was one part where Simon explains why a 9 could not be in the upper right corner in the center box using 2 processes of elimination. There was a 3rd elimination in that a 9 was in box 7 on the diagonal line and thus the 9 could not repeat on that line.
super satisfying solve!!!
This was just the right level of challenge for me!
at 15:45 the domino that could be 91 or 97, the 91 is divisible by 7 and 13.
Beautiful puzzle and a beautiful guitar intro
I love the prime number restriction!
i like the new intro music really much. i hope it will stay for a while :-)
greeting from germany
Didn't solve it nearly as fast as you, but I'm proud to have found that 7s trick myself!
that guitar was such an unexpected treat :)
What a puzzle! I had to spend multiple tries to get this one.
Another Aad masterpiece.
Simon is much more experienced in sudoku than me, but I seem to be more experienced with primes. I was yelling (internally) about combinations that cannot be prime throughout the video.
I don't understand how you ruled out a 9 from the center cell at 17:17
that's where I got stuck on my attempt
The central cell is the only place a 3 can go in the box.
The 3,7 pair in box 4 rule it out from the top row. The 3 in box 7 rules it out from the bottom row by normal Sudoku and from r5c6 by king's move.
It's really impressive how tight the logic is at the beginning; my logic was slightly different (I realised the only prime number to begin with a 7 was a 9, so 7-9 had to be together somewhere in the magic square), but the steps were nearly exactly the same!
Think you have that the wrong way round?
97 is the only prime in the 90s.
71, 73 and 79 are all prime.
@@RichSmith77 Yes, yes, I mistyped xD
I swear Simon always sounds slightly disappointed when he says, "and now we have to do some sudoku," after he runs out of other puzzle clues.
Your thumb nail is sick today🔥🔥
46:08 Really thought I'd have a better time, but I struggled mightily on the opening part of the puzzle (resigning myself to a couple bifurcations) before finishing strong.
I admit I had to get all the available prime numbers on google. Couldn't hold all that in my head. Great puzzle.
91 is interesting as the only non prime number less than 100 that doesn't have an easy check for being not prime.
If a number is divisible by 2, 4, 6, 8, 10 or 12 it's obvious that it's not prime because it's even.
If a number is divisible by 3 or 9 you can sum the digits and see if that sum is divisible by 3.
If a number is divisible by 5 it's easy to check that it's not prime (it ends in 5 or 0).
7 could cause issue, but 7x7 is square and pretty obvious. Then the only option left is 7x13 = 91. Anything else is over 100 (7x14 or 13x8 are over 100).
Therefore 91 is the composite number less than 100 that's mistaken for being prime more than and other number less than 100.
"If a number is divisible by 2, 4, 6, 8, 10 or 12..." What's so special about the even numbers up to 12?
Simpler to say "if a number is even then it's divisible by 2, so not a prime"?
Simon! Do you publish any of your music? Cause I could definitely chill with much more like that opening.
Love the guitar intro!
Well I have had my dose of “crack” today. Cheers mates.
it really was lovely, the addition of the primes and the offset magic square was a nice change. Simon it was interesting that there were several times where you wouldn't scan both legs of the Central × before you started following subsequent clues... is the fact that I did a deficiency on my part? how do you prioritize which clues you follow vs which ones you save for later?
I had a go and managed to work out that the 2 had to go in the top left cell, but then messed up the prime. I think I got confused with the combination of the magic square and primes and ruled out candidates that I shouldn’t have.
May I suggest you put the instructions on the puzzle page? I keep having to flip back to the paused video if I want to clarify an instruction, and it also makes it hard to share the link with someone.
Bah! I couldn't solve this one without the video... Tried to use it as little as possible, but couldn't avoid a bit...
I was pleasantly surprised by the guitar intro.
Simon's guitar
Love the Street Spirit intro music.
Loved it!!!
I got quite frustrated with this one. I figured out the magic square and got about half way through the whole puzzle... then got totally stuck about half way through. I guess I missed one of the numbers that was eliminated on diagonals but oh well. win some lose some lol great video
For someone who memorized the list of primes below 100, seeing that 9 in the 2nd box and not the 7 right after it is agonizing. There’s only one prime number in the 90s and that’s 97. 91 is divisible by 7 and 13.
I didn't manage to solve the puzzle by myself, but it was definitely a brilliant one.
15:15 91 also isn’t prime in Box 2
At 14:18 he removed the 9 from r4c2, but left the 9 in r4c1. I can't see how that was justified.
It's because R1C2 doesn't see R4C1, so it's possible that both of them are 9... If you forgot that 9 now can't appear in the magic square twice, which I forgot until just now, and I bet Simon forgot that in the moment
I still don't see how he removed the 9 from r4c2. Without that he can't proceed the way he did. Since he found the 9 in the magic square, then that would remove the 9 in r4c1, not r4c2. Help me see..., please, because I be cornfused.
NM, I went back and reviewed it. I get it now! the 9 was removed due to the possibles for 9 in box 1. Either one would preclude a nine in r4c2, one via sudoku rules and the other via kings move restraint.
"6,6,8,8, check" I believe you are supposed to say checkmate when dealing with finished king!
Is that an original song? Does it have a name? Loved it.
I'd love to see more guitar intros, they are really, really awesome
Two and a half hours (with help). I suffered because of too many pencil marks. I should listen to you more closely!
Brutal!
If I see a puzzle by Aad van de Wetering I know it's beyond my current ability but I am working on getting to that level
Believe in yourself! I recommend trying to solve it, and using the video if you get stuck. This is one of the simpler Aad puzzles not requiring advanced techniques