Triples: the Single Most Important Sudoku technique?

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Hi! We're Simon Anthony and Mark Goodliffe, two of the UK's most enthusiastic puzzle solvers. We have both represented the UK at the World Sudoku Championships and the World Puzzle Championships. We're also "cryptic crossword" aficionados. Mark is the twelve-time winner of The Times championship and Simon is the former record holder for most consecutive correct solutions to The Listener crossword. We hope we can help your puzzle solving while also introducing you to some of the world's best puzzles.
Thank you for watching!
Simon and Mark

[@prexzan]

I struggled through, then watching Mark re-impressed on me just how incredible at Sudoku he and Simon are with recognizing the paths forward.

[@BlakeMcCringleberry]

Very fun puzzle today! The triples weren't obvious at first, but once they started appearing, they totally led from one to another, and the puzzle just opened up very quickly.

[@ryanager8029]

Agreed, took me a minute to see them, but once they appear, it’s a spiral to the solution

[@susanne5803]

Favourite Mark moment 10:59: Pencilling a 2-4 pair in box 4 containing a 4: "So - those are a 2-4 pair ... is that ... urgh ... Please help me ... Don't just be ... showing an interesting pattern and not actually helping ... ehm ... Okay, that is a bit frustrating ... I don't actually see what that gives me ... But it looked incredibly interesting ... Maybe one of these 2-4 pairs actually does do some work ... ehm ... 2 is in one of those cells ... And partial enlightenment finally happens 11:46: "Ah ... 4 in this box has only got one location ..." Resolves this via box 6, finally writes a 2 in box 4 and still doesn't see the 4 that was sitting there waiting to be seen all this time. I just love this channel to bits. 😊 Thank you so very much to all the setters and to Mark, Simon and Sven!

[@Sarah-im2md]

I'm so happy, your video comes with the best timing! I recently started solving Sudoku and I'm lacking basic rules / tricks to solve them. Thank you for your content, I always enjoy it

[@arimyllyniemi8445]

Thank you for the well documented solving of the puzzle. Now it was a joy to follow your technique and learn of it.

[@Coyotek4]

38:43 ... this one really worked me over. It took me over 10 minutes to get my first digit, and it was mostly a slog from there. That said, I *did* find the triples alluded to in the video's title, and I *did* finish this with no guesswork. I'll take it. Tough classic!

[@mary-jolough9174]

I’m new to all of this. I understand the difference between corner and central markings, but why keep both in one cell?

[@Coyotek4]

@@mary-jolough9174 It's the difference between the two which is the reason to have both. Example: you have two cells in Box 4 corner-marked with "7", and one of those two cells has "79" central-marked. Later, you learn that the other cornered "7" is the 7; now the central mark tells you that cell has a 9.

[@cathypoole3015]

Finally starting to wrap my head around triples. This one helped a lot.

[@sandyhafenbrack141]

I loved this puzzle. It was so much fun finding all of the triples and this was at last a puzzle that I could actually accomplish on my own the first time I tried it.

[@phillipcarlroberts4640]

Thanks for the puzzle, you guys are pros and you have taught me a lot regarding sudoku's, Cryptic crosswords and simply maths in general, its my favourite channel on youtube 😀, you guys keep churning out great content on a daily basis...homage to you.

[@ronaldkoh5281]

Excellent easy paced demonstration. Ten thousand thanks. The best sudoku master that I am learning from.

[@VeritasUnae]

There's a lovely flow to this once you spot the break-in points, and as always it's delightful to see Mark's impressive solve. If I'd had more time I'd have attempted it myself haha

[@seanmcdonough2683]

11:20 Absolutely killing me marking up that cell ignoring your Snyder notation on 8s

[@menbah]

He even high lighted it with a line straight down towards them! =)

[@drstkova]

I was thinking “Am I stupidly missing something that’s preventing him resolving the 8s?”…

[@R-N88]

Haha yes me too 😜

[@zacharysherry2910]

Lol

[@bape7372]

Bro sameee

[@MisterM2402]

This one was tricky, I only managed two decent deductions myself: 1/9 pair in row 2 (the inverse of Mark's triple) and 3/6/8 in column 1 (again, the inverse of Mark's triple).

[@tiithendrikpiibeleht4092]

10:28, it was hard to get going, but after 5 minutes didn't get stuck anywhere. Thanks for the nice puzzle!

[@gregs2284]

FYI a weakness I've seen is that Mark it seems still isn't after all this time accustomed to the corner marking technique. At 11:11 he highlights the 68 pair in box 5 and stares at it for a while but never notices that he already corner pencil-marked 8 in to cells in box 8 that this pair now decides.

[@SamCoca]

This was a fun puzzle. I really enjoyed the old app better. Thank you for giving us a classic.

[@howhardcanitbe7018]

Great puzzle, 35:51 for me. This one was really tricky, took me longer than I think it should've. Mark's time is really impressive, and those of you who did it around the 10 minute mark I'm pretty sure are from another planet.

[@loganv0410]

Listening to your thinking has made me much better at this (at times) very frustrating hobby

[@harrysurtees8710]

It took you four minutes and four seconds to see the 6 and 8's that eliminate one of the two eights below. You can't see the trees for the forest. There are so many numbers it boggles my mind. Sometimes when I get stuck, I walk away, and when I come back later and the answer (number) is so obvious. Thank you for helping me with the techniques, and what to do with triples. I think my biggest problem is how to recognize triples. Thanks again, you are a big big help.

[@harrysurtees8710]

At 14:13 you found the 68 pair ramification. One thing learning to solve sudoku, I never hear anyone talk about the first thing I learned? After I saw where the BIG 8 went in row 7, I looked at every BIG 2 and easily saw that all the empty spaces in row one were blocked by a BIG 2, except one. After that I looked down and saw where another BIG 2 goes. From there on, I was off to the races. Sometimes even a blind dog finds a bone, every once in a while. Thanks again, I appreciated what you do.

[@Raven-Creations]

Nice classic. Mark had a few scanning failures, such as pencil-marking a 24 in a box with a given 4, and not spotting the 68 looking at a corner-marked 8 for a while. They weren't that important, but did slow him down a bit. Apart from the triples, I think the key was getting the 24 pair in box 2. It all seemed to open up after that.

[@ColinHolloway70]

It's always amazing looking back at these older videos. 9:09 is a Phistomefel Ring on 2s. There's only 1 2 in the outer boxes in r1c8 and 2 to be placed in r3 and r7, so r1c9 must be a 2!

[@cyanah5979]

For me the most vital was the 24 doublet in the middle upper square. Once I got this the puzzle resolved very quickly.

[@miroslavapaleckova838]

23:37 I'm always so proud of myself when my time is close to video time :D

[@TiagoMorbusSa]

This puzzle was an absolute monster, only Mark could solve it this fast!

[@girishgupta2938]

Sudoku Club

[@bala1000mina]

I enjoyed and really learnt a lot from this video! Thank you so much Mark! Good luck!

[@balkthor]

16:23 for me here. Pretty proud of it. I found myself playfully cursing at the puzzle's genius setting about a dozen times when I pieced together sets of quads/triples/pairs.

[@deedemarest443]

Really appreciate that you actually pronounce it correctly and smoothly Sue-doe-koo a Japanese word (without over emphasizing "dough") as someone else who has a youtube video and insists on pronouncing it wrong saying it's a US pronunciation which there is no such version! He also gives an American all the credit for it's invention, but there is actually information that portrays an interesting history it's very first concept was created by a Swedish man in 1800's, later placed in a French newspaper, then refined in America but actually made popular in it's current form by the Japanese and called Sudoku.

[@shteebo]

Thank you for mixing in the occasional instructional video. It's very helpful.

[@dismalfailure44]

The trouble with triples was right there!!!!

[@glennmelven3414]

But he already did it.

[@olamarklund1755]

He was on the right trek!

[@davidhughes7174]

Wonderful solve Mark. A great sudoku lesson. Thank you

[@SmartHobbies]

Nice example of an enjoyable classic sudoku. Nice solve path.

[@shirleyhenderson155]

Info re: triples (which I'd discovered by playing many, many games, but didn't know how to use to my advantage) was so helpful. Being intentional about finding them helped me solve in 23:21 on second attempt. Yay!🎉

[@Magemasher256]

Great solve as always!

[@kkob]

Great video. I'm basically self-taught on Sudoku. The basic techniques seem really obvious, right? Still, I sometimes have had to resort to trial and error because I can never remember the advanced techniques, such as X wing. Your way of starting with only the isolated numbers was very useful. It took me two restarts, but I got it on my own, but that one simple way of starting really helps. Cheers

[@hhsc09]

Usually struggle with some of the classic techniques, but this one went well for me today. Instead of the triples, after my initial corner markings I quickly found that 1&9 were restricted to 2 positions in R3, then that 3&6 were similarly restricted in C1. Felt a little more powerful this way. It gave me a few digits then pairs started flowing into each other and cracking the puzzle. Finished 16:17.

[@petslife3533]

nice will try

[@tarunieminen1533]

Thank you, very instructive. Can't find a link to try it out myself, though.

[@jeffbrunton3291]

Good puzzle. Took me a long time but didn’t require anything too complicated

[@crusader5951]

Classic sudoku is my weakness. I color the parity even/odd in this puzzle and help me a lot to spot the restriction. Tough puzzle but i solved it!

[@MBSPUHR842]

30:28. very nice puzzle with triples (and a few doubles and quads) leading down a straightforward path. I'm just a LOT slower than Mark in terms of scanning and finding them.

[@stegra5960]

I'm shocked! I sailed through this one far faster than Mark. Unheard of me. I've been known to spend hours on some of the variants. I used the NYT trick a few times near the start and rest fell into place.

[@patrickolsson6801]

I'm guessing we had to have Mark do this puzzle so that we didn't hear Simon singing twice during the solve? =D On a serious note, I love watching your minds work, as they unravel the web of logic! Keep up the great videos!!

[@EliChristman]

It's good fun to watch all your videos, but I myself am probably restricted to traditional Sudokus. This is the only puzzle I've seen recently I'd stand a chance to complete. In about an hour. I'm only an ameteur. ;-)

[@LednacekZ]

i found 2 sets of triples. Not bad for an usual classic, sadly for this sudoku it was 2 out of 100.

[@sjefjansen4696]

Please make more classic Sudoku puzzle videos!

[@regibson23]

Why does your website app not put the notes in a consistent corner? 1 should always be top left. 9 should always be bottom right. Etc.

[@r0bw00d]

I quit after 35 minutes. Once I got Row Three filled in with its pair and triple, I couldn't find anything else.

[@susanne5803]

You're not alone!

[@invictus9976]

Thank you.

[@deedemarest443]

Process of elimination in a column find the numbers missing and then cross check the intersecting row because any of the missing numbers that show up in the cross section have to be eliminated too the rest you can note in the box, do this to each cell in the box of 9 and you will have found all the possible combinations for each cell. As you fill in a number you have to eliminate it from being possible in the others. As you go along you will find only one that can fill a cell and reveal the correct number in another. You will notice the more difficult ones will have multiple boxes with the same missing combination of numbers so you have no choice but to use this process.

[@CMLachky]

Great Puzzle!!

[@Gonzalo_Garcia_]

17:56 for me. It took me a while to find the first triple, then it was much easier from there. I consider myself to be pretty bad at classic, so I’m happy with this solve.

[@leonr2964]

I managed to get under the 10min mark

[@boskinspace4263]

Took me over 80 minutes on my own, but then came back to watch the under 20 minute solution (just to check). So fast! 😮😮😮

[@Tombsar]

Nice classic puzzle. Reasonably difficult, but not too hard given the video title that primed me to look for triples. Took me 20 mins.

[@suris5893]

Like your honesty

[@dilbert719]

28:20, only after reminding myself that the title of the video was triples, and maybe I should start looking for some hidden triples across the rows and columns with 4 givens.

[@twigd3825]

i always have a hard time finding triples so before watching mark, i proceeded to solve this puzzle. that 1/9 pair was very easy to find without the 356 triple and it set up the 3/6 pair in column 1. from there i needed nothing but pairs to solve this puzzle. got to find a harder puzzle that could only be solved by triples.

[@rabidsamfan]

I solved that old world hardest puzzle once. Took a month to do it logically but boy was it amenable to two good guesses.

[@zafmahmood5654]

Someone please explain why the guy selected the 8 in the first column (TIME 10.02) where he did?I know from the rules of Sudoku that there are two 8's in the first column rows 4 and 5.But why there.....and not the one above it.Thanks

[@wbball15]

6/8 pair in b5 gives 8 in b8

[@charlesmangum2100]

68 in middle row. Finally

[@chrismoyler]

At 11:16, Dont the 8s in the centre box define the single digit 8 in r7c6 and the 8 in row 1? You found it at 14:18! Tky dear Mark A very interesting puzzle.

[@benjyletouffu]

Hello, there's a technique that you guys are using and don't quite understand how yet... 3:51 and 4.44 you marked 3-6 and 4-7 by counting 1 to 9 in both row and column, how does this technique works?

[@calzoncillo17]

There has been a recent glitch on the iphone version of the app, it zooms in and doesnt zoom out

[@ffmuller]

Very impressive but need to teach as you go. Lost me at 5:20 with the 5’s. How was that made?

[@miraculix666]

Mark had "Troubles with Trip/bbles".

[@georgebaader9817]

At 3:50 how do you know that it must be a 3 or 6 at row 3 column 4?

[@georgebaader9817]

oops! found it

[@moxed42]

@@georgebaader9817 Can you explain?

[@moxed42]

Oh! I also just got it. For others reading - all other digits are in a crossing column/row and are eliminated by basic sudoku rules

[@squallerrleon]

27:23, one hint. Overlooked a pair/triple I had marked in C2. This is probably the hardest regular sudoku I'm capable of now

[@deedemarest443]

Eventually if you stay at it no matter how many missing numbers there sooner or later you will find the one that begins the domino effect until it's solved. I guess the only other achievement is how fast you can can solve it.

[@shulemankhan5461]

Very nice

[@coyote4237]

Thanks.

[@johnwilliams3555]

I am bamboozled! How did you arrive at 3/6 option at the 4:50 mark?

[@mbala6360]

for that cell, only 3 and 6 left if you look at the column and row

[@elisabethloxley6124]

Very tricky, I would not have solved it as quickly

[@drumbyte]

Amazing!

[@rosiefay7283]

How do triples help? My solver was able to solve it using only naked and hidden singles and pairs. Its first 2 deductions were R3's 1 and 9 are at R3C1 R3C5, and C1's 3 and 6 are at R1C1 R4C1 (hidden pairs).

[@b.k.7573]

35:34 ....... Nice puzzle to solve. The triples kept popping up left and right, which obviously was intended lol but helped me a lot to solve it :)

[@deedemarest443]

The idea of creating boxes with the same missing numbers across and down makes it more difficult to solve along with providing less numbers to start with. I enjoy the challenge.

[@Jodawo]

On Sudokus with variances Simon might be considered the "Sherlock Holmes" of solvers. When it comes to Classic Sudoku Mark is "Monk" without all the OCD... LOL I think it was a great solve. Very good catch of the triples only one glaring miss, of significance, the 68 pair that really didn't give away too much when finally seen. I do believe this would be the type of puzzle a person could get stuck on for hours but Mark made this look doable. I do see where many want to compare both solvers (Simon and Mark) by trying to put them against each other. You have to remember they both have their strengths and what you saw in this puzzle is right in Mark's wheelhouse.

[@muskyoxes]

I wouldn't be stuck for hours - i'd fill in every candidate in every cell long before then

[@harrysurtees8710]

I disagree with your 68 pair assessment. Look at the puzzle when he discovers the 68 pair (14:13) eliminates the one 8. What I did then, looked at all the big 2's in each column and saw they covered every blank space in column one, except in row nine. Fill in that 2 and I was off to the races. It took him 4 minutes and 4 seconds to see what 68 pair did. That was the key for me. Of coarse, I needed help finding the triples. I do struggle most of the time.

[@kathleenliegeois9925]

Good evening, Can we succeed a Sudoku of all levels without detecting hidden triplets ?, I have trouble recognizing some of them, at least for the hidden ones.

[@alanclarke4646]

Very fun to do

[@davidh.4944]

49:17. It was quite a tricky game. Not difficult, per se, just very hard to spot the combos. Being tired and sloppy with my pencil marks didn't help much either. Still, classics are the best to do after a long day-as long as they aren't too hard.

[@JohnRandomness105]

1:50 I misheard you describe the author of the puzzle as "finished". Sorry about that. 11:35 The 68 pair you just glanced at fixes an 8 in B8, then another 8 in B2. (Some time) The 24 pair fixes the 6 in C4. 18:30 Why did I miss the 3 being fixed on column 6, that resolved the many 37 pairs? I had to resort to colors to finally show that a cell with a 37xy faced both 3 and 7.

[@peterosborne3700]

Thanks

[@CrackingTheCryptic]

Thanks so much! Really appreciated.

[@mostlyharmless6168]

I really appreciate an occasional classic!

[@sudarminthen801]

@5:16 how did you know there will be no '5' in the second colomn third row? as far as I try to see that box can contain 1,5,9, how can it can be decided no '5' in that box?

[@sudarminthen801]

oh got it, if you put '5' in that box, there will be nothing on the third colomn third row

[@zygfrydmina8419]

40:05 for me, completely on my own. I see that as an incredible achievement.

[@guyb7005]

17:00 "that can't be a 6..." not sure how you came to that conclusion. I think I see it but you don't clearly explain it?

[@bernardfinucane2061]

That 68 pair in the middle box was so distracting!

[@jacktheripperd1141]

i don't understand the logic at 9:58. How does 178(R1C5), 179 (R1,C7) and 179 (R1C9) mean R1C5 is 8?

[@yen-chewu1467]

19 (R3C1), 179 (R7C1) and 179 (R9C1) mean column 1 (including R5C1) can't have 1, 7 or 9 anymore

[@IanMcGarrett]

After finding the 19 pair in row three I erased the corner marks and the 386 triple in column one stood out.

[@palacerevolution2000]

Every time I thought I'd cracked it, and found my way in, I got waylaid again. This was a tough one.

[@killer408cid]

I average 9 minutes on evil level sudoku, but I don't think I ever really noticed the significance of triples as such. I'm eager to apply this and see where it takes me.

[@RO8s]

Well, when I started Sudoku, I discovered triples by myself, but he found a quadruple which has never occurred to me! I'm glad he had difficulty - I had to bollox the whole thing out and do it from there. I did it, mind!

[@brandonfisher5303]

44:20 with lots of help from mark lol

[@michael4962]

The triples confused me. I wish you would slow down a bit when you are applying a rule instead of just filling in the numbers and saying what you are doing. Explain what you are doing please.

[@swimfit57]

That puzzle was a tough one!

[@kwikstah]

I don't understand the logic at 16:52 that allows mark to place pencil marks at r8c6 and r9c6 as (1,3,9) thus eliminating 6 as a pencil mark.

[@trenthogan4212]

but you never explained what triples are and why they work....

[@964cuplove]

2:18 start

[@Sibula]

24:02 had to centermark the whole grid before I found the critical triples

[@wanderlustwarrior]

I restarted the puzzle after I thought I broke it about 33 minutes in. Solved it on the second attempt in 24:05. Classic sudoku somehow feels like a strange challenge now.

[@prexzan]

Hah! I was wondering where I got the hint to look for triples! Need to pay more attention I guess :)

[@wanderlustwarrior]

16:17 for me this time, much better.

[@scarcesense6449]

Well, I solved it. But your way looks a lot easier. I've never really used notation.

[@CH4NNELZERO]

81 minutes for me. I solved it via doubles, not triples. Still needed a hint to find the last 6/7 double in column 2 which finally finished it.