The Killer Sudoku Of Prime Numbers

[@constanza1648]

It was hilarious... "no, no, no" Me: What happened? Did he break the puzzle? Simon: "That stopped to be a 3 in the corner"

[@steve470]

46:41 for me. Wow, there was a lot of beautiful logic in this puzzle. Also, the 49:54 mark of the video is peak Simon. Struggling to resolve a 1-6 pair, moving his cursor directly to a 1 in one of the relevant columns, and yet still not noticing it. Ah, Simon, we love you.

[@Coldheart322]

Yep, saw that too and was just laughing, wondering where he was looking, or what he was looking for, while hovering the cursor over the answer. Edit: Sigh of relief. I was wondering if Simon would somehow work out where the 6 went, instead of using the 1, which is another nice trick of his.

[@BeatingBat]

Simon coming to absolutely mindbreaking conclusions while also forgetting to take account for the basic rules of sudoku is oddly comforting. Great solve! (just to be clear, watching Simon solve is incredible, the logic working in this man's brain is next level)

[@ingiford175]

Just like when he has a 16 he wants to get rid of one of the solution, the mouse is over the 1 that will reduce it as he shakes the mouse in frustration that he cant find anything that reduces it (just after 50 minutes in)

[@CrankyOtter]

@@ingiford175I’m yelling “find your cursor, Simon”. It’s incredible how often it’s positioned where he needs to look.

[@ingiford175]

@@CrankyOtter almost half the time the solution seems to be under that cursor.

[@jenniferlenfestey5335]

I start my day with Mark’s wordle in a minute, and I am absolutely amazed at how fast his mind can assimilate the remaining letters into a new word, but today was tough, and his sign off at the end was very difficult to watch.

[@davidmiller9485]

i normally don't watch them but thought i would go see what Simon was talking about... I got it after his third attempt. I still listen to the music of my youth so disco and 80's electronic (Go Flock of Seagulls) are fresh in my mind so it wasn't quite as hard for me. I did feel for him struggling though.

[@andrewnelson2525]

When Simon declined to do parity coloring I was disappointed but confident he'd eventually get around to it. But he didn't! When he used coloring for the roping but still not for the parity it was like a stab to the heart. I attribute my use of coloring for the fact that I came to within five minutes of his solve time.

[@novemberdag1127]

I love how Simon flips if he might be stuck by hovering the cursor on the number he needs to disambiguate a pair (the 1-6 at 50 minutes for instance) Absolutely adore this channel

[@tchpowdog]

I just watched Mark's Wordle video lol He was so ready to turn the camera off! I love the videos where Mark struggles. I don't know why. He's such a genius and I have the upmost respect for him. But I think it's because he's so genuine, and lovable, and warm that it's funny to see him out of his element.

[@aleksandrajanicka6949]

One thing I was missing during the video were the thoughts around modulo three. A lot of low odd numbers are not prime because they divide by three. For example, a 17 pair in R7C6 was giving the same modulo when divided by three and that could already put a 39 pair in R7C7 and R7C8 and a single 5 in R7C9. And the other thing I expected to be exploited near the beginning was when it was identified that in box 4 each 3-cage must've contained 2 evens. Every 2-cage must contain exactly one even so, together with R6C9, it would've consumed all the evens for row 6, giving a quite early information that R6C4-R6C6 cage is full of odds.

[@MisterM2402]

1:17:25 for me. That was a trial! All the deductions were nice but I have a bad short-term memory so working out all the possible sums over and over again was quite painful.

[@stephenbeck7222]

The way that column 9 resolved was really amazing. Love some good killer sudoku.

[@KeiFlox]

I'm a newer fan of the channel and while I do watch Mark's daily Worlde videos, this was my first time seeing him struggle! I don't play Wordle myself, but I like to "play along" in my guesses as I watch his videos. I couldn't think of anything that would've worked, still impressed that he managed to find the word in the end!

[@cossin281]

This puzzle was fantastic. There are lots of beautiful deductions, even if I had to write down every possible total for each size of cage to see them. Struggled a little bit with finding how to break into it, and then more with how to continue out of the initial cascade. I was tempted to go back to the video for the next step like I usually have to do (even if it was just to see that I misread a rule yesterday), but I managed to finish this on my own and somehow got a time of exactly 70 minutes.

[@letsmakeit110]

Took forever, broke it once, but I got there in the end, which is more than I can say for most of these. Approachable.

[@Bonehead777]

I solved another absolutely fantastic, but blooming hard prime number based Sudoku by Farkov. It’s on LMD as ID DCK and is called The Subprimes fiasco. If you want another Prime Number challenge, it really does deserve more solvers. 🙂 In the meantime I shall lie back and watch this one solved by Simon. I love Agent’s puzzles.

[@titusadduxas]

1:57:54 - I didn’t have a clue how to start this but after watching Simon suggesting it was a parity thing I was off to the races. Some truly fantastic logic here, though some of it took me a while to spot.

[@letMeSayThatInIrish]

What a beautiful puzzle. I always wanted a puzzle like this, based on prime sums. This was extremely satisfying!

[@MyriamTT]

Killer are one of my favorites. And this is rally a brilliant puzzle.

[@Anne_Mahoney]

I love the arithmetically-focused ones, and I'm very fond of primes! What a treat.

[@DWestheim]

That was a neat treat for a prime number nerd like me. Yes, I'm also a blast at parties.

[@ejvalpey]

I often start these prime number puzzles making lists of primes but never really end up using them. It’s primarily a parity puzzle with a little bit of mod 3 logic thrown in and a few spots where 25 would otherwise show up.

[@stevieinselby]

Yes, unlike the GAS today where you needed to bear in mind all the prime numbers up to 97, including all those awkward higher numbers where you don't necessarily remember whether they are prime or not, mostly here we were looking at numbers below 20, and so most people will fairly easily be able to hold in their heads which ones are prime.

[@stangerrits6712]

Luckily all those prime numbers where mentioned in the rules of the GAS puzzle 😅

[@willemm9356]

From a mathematical standpoint, 7x7=49, so all non-primes that are 45 or below have factors of 2, 3 or 5. So you're right that parity, mod 3, and ending in 5 is all you need to check for primeness in this puzzle.

[@CrankyOtter]

I’m halfway thru and at no point have I predicted your next step. Usually by now I can see how it might unwind but this puzzle is above me.

[@CrankyOtter]

For number fun in box 3 col 8 3 consecutive single digit odds aren’t prime, nor is every other. The rest are prime. Not prime sums: 135,357,579,159 Are prime sums (the rest): 137,139,157,179,359,379

[@EmperorIcePenguin]

for the odd and even marking, you could use the line tool to make a circle and cross for a known even/odd and maybe a dual square color if a square could be both.

[@formidable4748]

Hello Simon, I'm new to the channel and its amazing how the challenges exhaust my brain while your voice soothes it to sleep 😂

[@Jodawo]

This puzzle is much easier than Simon makes it. A lot of it is narrowing down the pencil marks. A lot of times you'll have multiple possibilities but you can eliminate most of them. It seems Simon abandons simple math every chance he got. (Simon loves to solve a puzzle using calculus when simple addition would do the job.) This puzzle is a very good puzzle a lot of logic. Other than not taking the low-hanging fruit Simon did an excellent job solving it. Hats off to Agent for creating such a fun puzzle for the math lovers.

[@mrrobotman5299]

Thank you. Normally a video this length implies that the puzzle is a bit beyond my reach. Your comment led me to try it. I was an hour in an realized I made a bad logical error very early on. I had to retrace a lot but finally did the puzzle. The worst part was my error turned out correct in the end but for much more logical reasons.

[@Jodawo]

@@mrrobotman5299 I'm glad my comment helped.

[@longwaytotipperary]

Very clever puzzle!!

[@PauxloE]

Nice break-in with the roping. I guess I made some mistake at some point, because after ~ 95 minutes the 3-cage in the middle needed a 3 and 5 in it, but the 9 was not possible. I'll retry tomorrow (and watch the video after that).

[@PauxloE]

On the second try it worked. (I made heavy use of the Killer Calculator - not sure whether that actually made it easier or just slower.) 117:50 the second time, solve counter 2020.

[@RoderickEtheria]

When Simon announced being stuck a bit around 27:00, his cursor was hovering over r4.

[@CrankyOtter]

My instincts for parity puzzles range from backwards to nonexistent so I enjoy seeing Simon suss them out.

[@Piatato]

Great puzzle, looking forward to watching!

[@moocowpong1]

One trick for doing this puzzle is to note that the total of any arithmetic sequence of length 3 or more is composite. For odd lengths, it's the length times the average value, and for even lengths, it's *half* the length times *twice* the average value. For the middle cage in box 8, Simon was looking to make a prime out of 3, 5, and another odd number, and this lets you see right away that 1 and 7 don't work, because 135 and 357 are arithmetic sequences, so the totals are 3x3 and 3x5 respectively.

[@earlmaudrie8650]

The fact that you know there are only 5 odd digits helps a lot with determining where the even digits in row 4 are, which the lets you find the evens in row 5, which lets you determine the parity of the rest of the digits in box 5. I'd definitely recommend coloring parity for that reason.

[@JeffreyLByrd]

This is the hardest puzzle I’ve finished, and it took me ages. Interestingly enough, I didn’t really have to think about parity until the end in the top three rows. That required leaning harder on the math and then listing the possible combinations, but that’s definitely slower. Parity gets you there much quicker.

[@martysears]

Well done Agent, I can't imagine a much better prime number puzzle than this... so pure, elegant and varied

[@stefanosmoringa6517]

Dear, SIMON the puzzle seems to have multiple solutions, in box 3 the middle cage can add up 11 or 19 and the middle cage sum will be 17 and 23 respectively.

[@finnfreudenberg5568]

Wow, incredible Sudoku. I did need 150 min even with a bit of cheating. It also kept its difficulty till the end.

[@flora5090]

Oh I was literally constructing something like that the other day! Happy it's already been done and with such a lovely solve path

[@emilywilliams3237]

A very interesting puzzle and a great solve! I always feel that, whenever you or Mark uses parity in a puzzle that is not obviously a parity puzzle, I learn so much. Thanks, Simon!

[@brianroberts7096]

I haven't done that much Maths with Prime numbers at any time in my life. Seriously got the brain cells working. Brilliant idea. Had to backtrack a couple of times, but got there in the end. Sent the link to a friend who thinks He's smart 3 days ago. Not heard from him yet.

[@Radinden]

I think that may be the most fun I've ever had with a puzzle that's taken me over an hour to solve: 67:02, but I never felt like I was stuck at any point, and some of the logic was genuinely beautiful. I can't even begin to think how that was constructed.

[@piarittersporn]

Brilliant puzzle. A few days ago I gave up, finally I solved it today.

[@jodysteele5135]

I was trying this one but I got stuck. Your hint about parity, combined with the secret, was what i needed to get unstuck and solve the puzzle :)

[@themiddleones11]

Parity coloring for column 3 really helped

[@DOSSTONED]

Wow, this rule is quite strong but hard to solve! I need to open a spreadsheet and put all possible combinations of primes on the list, this helped a lot especially when you want to find the remaining digit to make the sum to a prime. It also reminds that the Sudoku rules is to help you to reduce possibles, the prime rule may give some kind of a map that even start and end places are close, they are not directly connected, you have to take a long run to get to the desitnation

[@Li3Kung4]

Over an hour with almost that much video watched. I needed lots of help on this.

[@inspiringsand123]

Let's Get Cracking: 07:37 Simon's time: 50m39s Puzzle Solved: 58:16 What about this video's Top Tier Simarkisms?! The Secret: 6x (07:46, 07:59, 08:01, 08:21, 17:18, 54:28) Bobbins: 5x (26:07, 34:10, 55:14, 55:17, 55:17) Three In the Corner: 3x (20:21, 34:10, 50:17) You Rotten Thing: 2x (34:16, 34:58) Maverick: 1x (05:32) And how about this video's Simarkisms?! Hang On: 12x (15:40, 15:40, 15:40, 15:43, 22:40, 30:11, 32:23, 33:54, 34:05, 34:16, 41:10, 53:11) Ah: 10x (11:03, 11:23, 14:27, 20:35, 25:49, 31:32, 32:06, 43:31, 47:28, 56:43) Sorry: 9x (10:47, 11:03, 16:01, 24:24, 26:33, 26:33, 27:58, 53:16, 53:16) Beautiful: 8x (17:49, 22:23, 22:26, 41:04, 43:59, 48:14, 48:37, 53:50) By Sudoku: 7x (15:09, 25:12, 40:53, 41:13, 43:46, 48:27, 51:31) Bother: 6x (35:56, 43:21, 44:38, 44:38, 44:38, 47:28) Wow: 5x (34:16, 36:00, 36:04, 36:12, 51:49) Clever: 4x (37:05, 37:07, 51:39, 56:45) Obviously: 4x (32:51, 35:43, 47:47, 49:13) Naughty: 3x (04:02, 04:07, 13:43) Brilliant: 3x (05:36, 58:14, 59:18) Pencil Mark/mark: 3x (32:06, 32:11, 37:57) What on Earth: 2x (36:27, 50:31) Apologies: 2x (05:50, 06:14) Missing Something: 2x (16:09, 24:12) In Fact: 2x (05:16, 09:10) Cake!: 2x (03:34, 04:50) Naked Single: 1x (46:27) Horrible Feeling: 1x (16:09) Lovely: 1x (15:11) Break the Puzzle: 1x (52:24) Fascinating: 1x (17:52) Incredible: 1x (20:08) Ridiculous: 1x (00:18) Shouting: 1x (04:13) Disappointing: 1x (36:04) Progress: 1x (36:30) What Does This Mean?: 1x (20:28) That's Huge: 1x (12:06) Most popular number(>9), digit and colour this video: Twenty One, Twenty Five (9 mentions) One (81 mentions) Green (5 mentions) Antithesis Battles: Odd (98) - Even (55) Row (15) - Column (11) FAQ: Q1: You missed something! A1: That could very well be the case! Human speech can be hard to understand for computers like me! Point out the ones that I missed and maybe I'll learn! Q2: Can you do this for another channel? A2: I've been thinking about that and wrote some code to make that possible. Let me know which channel you think would be a good fit!

[@Orenotter]

Prime numbers all over the place. In cages all dotted like lace. A small bit of roping Helps solve (So we're hoping). To finish, names flying through space!

[@arturocaissut1071]

This one was really though for me, but also really rewarding.

[@CuriousChameleon]

This break in for me took ages. I got started by figuring out it would have to be THREE (3) in box 6 R4C9 as the only option as you needed 4 pairs of prime numbers being an even number + that lone odd digit that would add up to 45. And the only ones that worked out high enough would have to eliminate all the other digits but the 3 as the odd digit. This in turn was beautiful. As there were now THREE sets of 13, one set of 3, and the other was the lone 3. I have no idea if this was intended but I found it fantastic setting (that was one of the options that could be possible). 13 + 13 + 13 + 3 + (3) = 45. I am one of Simon's favorite people as I knew the secret. \0/ I felt really smart and really dumb. That set me up slower but I feel like I got a digit not in the intended order so it was slow start but got faster as I was kinda ahead later down the road. Great setting Agent.

[@karsaanita]

Okay, this was awesome. Nice relaxing hour solving sudoku before going to bed.

[@mhbjarkistef]

After getting stumped on some of the harder puzzles on the various apps and books, are there any videos of Simon doing a hard "unconstrained" normal sudoku? His commentary and explanations on-the-fly are so fantastic, and just seeing a difficult sudoku solved in real time would help immensely.

[@stephenbeck7222]

Yes, search for ‘classic sudoku’.

[@rizka7945]

See the video desciption. Scroll to the bottom of it to find the CtC catalogue.

[@ericpraline1302]

Lovely jubbly, thanks Agent.

[@stetsonhendrix9103]

Excited to do this one!

[@stetsonhendrix9103]

Turns out this puzzle is really hard when you spend three hours forgetting that 2 is also prime.

[@matthewcunningham2278]

At 28:01 if Simon would just look at his pencil marks he has in blue it is possible to go through all the different iterations and find out that box nines t pentomino cannot have a two in it

[@gordonglenn2089]

Well, it took me 2 hours to finish, but I rose to the challenge and did it all using only mental arithmetic. I have to keep exercising this old brain! I did notice the roping right away, then went with parity coloring instead, as I started to see those few cells that I could easily deduce were odds. Now I will watch Simon's solve and see where I missed the chance for greater efficiency. Edit: His solution path was similar, with him getting a few aha's faster than I did, and (as usual) missing some obvious sudoku such as failing to notice the 3-5 in box 1.

[@Rach881101]

47:10 for me. Marvelous puzzle!

[@phuybrechts6875]

At 50.30 you went nuts , Scanning the 1 ( curser was on it 😮😮) ,4 in the corner , en 6/8 pair in box 1 ! For the rest a marvelous solve 👍

[@GianniBergandi]

42:18 for me, amazing one !

[@GuatemalanJedi]

When Simon doesn't even NOTICE Maverick flying by you know he's in the zone.

[@EbnuSuryadhi]

Incredible design by Agent!!!

[@fisher00769]

400 minutes for me I don't think I have ever stuck around for this long with a puzzle, but I never felt stuck, it was just not obvious, where to look next, I kept making progress, just slowly. Very slowly.

[@tommyisrael]

44:40 yea, i wonder? IT LEADS YOU TO THE NEXT STEP OF THE PUZZLE. RRRAAAAA. LOL 🥸

[@tommyisrael]

use the 'cat in the box ' on c8, start at the bottom

[@codragdus]

49:58 Are you kidding me with this R6C2 miss right now 😂

[@glum_hippo]

33 minutes for me. I love the parity arguments!

[@Raven-Creations]

@ 49:59 - "16, come on please" - you went straight from that 16 pair and pointed at the 1 you'd placed seconds earlier in box 1, which sees the 16 pair. How can you not connect the two? I was going to suggest that your memory is goldfish-like, but that would not be fair to goldfish. That was remarkable setting, full of surprisingly restricted cages. However, this is not my type of puzzle. Repeatedly working out which combinations of digits sum to a prime number is not my idea of fun. I'm sure there are some people who loved this, but not me.

[@andrewgrant6516]

I don't know, it feels like I've watched you solve this before. De Ja Sudoku.

[@ionguy2881]

Thanks for the birthday wishes!!!!

[@haflam.]

The power of Primes!❤

[@codragdus]

44:46 Simon! R6C3. I’m starting to think you do this on purpose because you know the endorphin hit it gives us ❤

[@torthorsen818]

Wonderful.

[@KestrelQ]

This one's a watch for sure but ain't no way I could attempt to even start this :)

[@mnvikings0527]

I can't believe that I saw the 46 pair in box 2 before Simon did.

[@stevesebzda570]

Oh Christ (Crikey's) a 1 hour video and Prime numbers . (Yes, and hour for Simon) Welcome to the math channel, apparently.

[@LednacekZ]

58:04 for me. Luckily, i realised right away that this was a parity sudoku

[@flsal27]

@12:37 This is a question for Numberphile: is there any mathematical series, that involves only even numbers that gives a result that is an odd number?

[@stevieinselby]

I don't know what word is missing from your sentence, but if it's "an operation" then yes, division can very easily involve two even numbers and give an odd result, eg 6 ÷ 2 = 3.

[@Gonzalo_Garcia_]

35:01 for me. Great puzzle, really enjoyable!!

[@lemlem35]

34:07 Most tragic occurrence a puzzle can have

[@tessabrisac7423]

😂😂😂

[@erickehr4475]

43:31 for me. I didn’t whizz through it, but never got stuck for too long either.

[@joaquins90]

That was hard, something about this puzzle made me miss every single time, 3rd time the charm was just a typo near the end while filling the last few cells 😅

[@darkreflectionsstudio4506]

You missed out of a beautiful piece of logic. When you had the parity of column 8 you could have seen that only one more odd digit was possible among those not already fixed as odd. Therefore, once you had the two 1/2, 5/8 pairs in box six, only one of 5 or 1 in the pairs could and also needed to accompany the 7 in box three, column 8. The 5 was thus already impossible, since it would need the 1 and not a 3 or 9.

[@MarcusTheDorkus]

Well.... crap. I spent 3 hours trying to work this one out. Only started to make some progress around 75 minutes in, but then just 15 minutes later made a fatal mistake that didn't reveal itself until I couldn't get a unique solution. I pencil marked the 4 cell cage in r7 but accidentally left out the 1, so I thought I could make r7c6 1. All I had left to place were the remaining odd digits in a few boxes when I realized that it was wrong. And just for the hell of it I picked one of the available arrangements of those digits and checked to find that the 4 cell cage I had mismarked was the only one that wasn't prime. It was one of the only cages I hadn't checked the math on as I was going... 😩

[@agargamer6759]

1:22:15 for me!

[@Mayank3083]

Can anyone tell me why he gets so excited for a 3 in the corner? Just curious

[@neilvan5856]

I would absolutely love to chat with you at a party!

[@Ardalambdion]

Only 10 seconds later, I joined this puzzle.

[@y_prime]

solved in 33:15 - lots of parity work this time

[@johngilbert7359]

OMG this one was hard.

[@bruceh8043]

Finish in 39:19.

[@robertcousins2274]

62:33 for me

[@AlexandreRibeiroXRV7]

The moment 50:00 makes me pretty sure that Simon has ADHD or something, he can't keep track of the numbers he was thinking about just seconds ago lol

[@martingayle5376]

Nice!

[@kwongshuchung]

1:11:44 for me 1543rd to finish

[@srwapo]

"You can add as many even digits as you like and you won't get to an odd number." If you sum 2x from x=0 to x=infinity, you sum an infinite number of even digits. Are you saying infinity is an even number???

[@tessabrisac7423]

Depends which infinity 😹

[@_-_-Sipita-_-_]

30:18 for me.

[@johnhumberstone9674]

You never reset the clock at the start, as Mark does.

[@glorkspangle]

Orange and blue are your friends.

[@patrickolsson6801]

49:58 come on please, a bit more. As his cursor is ON the 1 he just placed in box 1, and then again at 50:38 he HIGHLIGHTS the same 1! I love ya Simon but sometimes...

[@Pritchie45]

78 minutes

[@jansteyaert1]

Don't solve sudokus when you're sleep depraved... you make really dumb mistakes, lesson learned.

[@BlueCyann]

I'll be honest, this isn't my favorite type of puzzle, being almost purely "here are four potential options for this cage; which one doesn't violate the ruleset immediately". But I did like the parity. Took me about an hour.

[@elLooto]

Gypped! Im not Simons favourite people.... Its Saturday morning here.