Engineers Will Love This Sudoku

** TODAY'S PUZZLE **
IcyFruit's sudokus are all works of art and their latest is a fascinating twist on killer sudoku - the cage totals are only approximately correct! Shoutout too to Sofia for her incredible email about the effect sudoku is having on schoolchildren in Sweden.
Play the puzzle at the link below:
sudokupad.app/ay6r6mmu5w
Rules:
Normal sudoku rules apply. Digits may not repeat within a cage. Cage clues show the sum of the digits in that cage, rounded to the nearest multiple of 5.
** NEW SANDRA & NALA FOG PACK **
A bonus sudoku pack was released on Patreon this week of 5 fog of war sudokus to celebrate the arrival of spring (in the Northern hemisphere) from Sandra & Nala. It's completely free - just click our Patreon link below.
Other treats on Patreon include:
- the new James Bond sudoku hunt competition;
- Simon's latest forays into the world of Islands Of Insight;
- Mark's video looking at the new OneUp puzzle from Rodolfo Kurchan;
- his solve of Region Geometry by Emre Kolotoğlu (3hr 36min long...!);
- and Mark's latest solve of The Times Club Monthly cryptic crossword
/ crackingthecryptic
** GET OUR FOG KICKSTARTER DELUXE & OUR BOOKS **
Check out this link for the kickstarter books and Fog Novella we've created over the years:
coffeebean.games/product-cate...
▶ SUDOKU PAD - Use Our Software For Your Puzzles ◀
You can input classic sudoku puzzles into our software and help support Sven, the programmer responsible for the wonderful user interface we all use to play these puzzles everyday. The app also comes with 12 handmade puzzles from us:
iOS:
apps.apple.com/us/app/svens-s...
Steam: store.steampowered.com/app/17...
Android:
play.google.com/store/apps/de...
ALSO on Amazon: Search for “SudokuPad”
▶ Contents Of This Video ◀
0:00 Theme music & puzzle intro
1:48 New crossword video
2:00 Patreon update
2:20 Sofia's email
5:50 Happy Birthdays
7:51 Rules
8:37 Start of Solve: Let's Get Cracking
▶ Contact Us ◀
Twitter: @Cracking The Cryptic
email: [e-mail]
Our PO Box address:
Simon Anthony & Mark Goodliffe
Box 102
56 Gloucester Road
London
SW7 4UB
(Please note to use our real names rather than 'Cracking The Cryptic'.)
**************************************************************
▶ CTC FAN DISCORD SERVER◀
/ discord
▶ OUR BACK CATALOGUE - ALL CATEGORISED WITH LINKS!◀
tinyurl.com/CTCCatalogue
▶ NEW CRACKING THE CRYPTIC MERCHANDISE◀
teespring.com/en-GB/stores/cr...
▶SEND US PUZZLES TO SOLVE/CONTACT US◀
[e-mail]
▶FOLLOW US◀
Twitter: @crypticcracking
Instagram (for how to solve daily clues from The Times): crackingthe...
We also post the Wordle In A Minute videos on TikTok.

[@sofiaolsson1530]

Hi! Im the Sofia from the video! I was hoping the story could bring you Simon and Mark some joy, im thrilled to see everyone im the comments liking the story as well! I actually work at the school too but with a different class, and today one of my mums students saw me and came up to ask "when can we have another sudoku lesson with you?". Thank you Simon and Mark for your videos and thank you cracking the cryptic community for making this channel possible!

[@RecreationalCynic]

Solved this in about an hour. It was 78:55, but I rounded it down.

[@evanbasnaw]

A proper engineer will always round up to the nearest integer and then multiply by a safety Factor. Therefore I entirely filled the grid with nines to ensure that everything was covered at minimum.

[@evanbasnaw]

Someone should probably tell my manager that we are over budget and behind schedule though

[@PassionPopsicle]

😂 This is the best comment

[@CaptainSpock1701]

@@PassionPopsicle Agreed!

[@srwapo]

same!

[@boblambert8985]

🤣🤣🤣

[@tylercollins7953]

I'm an engineering student at university right now. I once had a professor that told us to round pi to 4 so that the math on one problem would be easier!

[@efa666]

Electronics? You can definitely get away with that much rounding in certain applications lol

[@tylercollins7953]

@@efa666I'm mechanical. I think it was my fluid dynamics class. All I remember is that the professor wanted to make pi = 4 so that the area of a circle of diameter 1 is 1.

[@mrrobotman5299]

In my classes we regularly rounded g to 10m/s^2.

[@akospapanitz8390]

@@mrrobotman5299 Yeah, that's a classic. The other we used at phisics is that sin(x)=x if x is close to 0. I've heard that this makes mathematicians go mad.

[@abcadef6171]

e = pi = 3, and if you square them, you get 10, which is also g.

[@MasterHigure]

Simon's joy when sharing The Secret with all his Favourite People, even after all these times, is contagious.

[@st0rmforce]

There was a video a couple of weeks back where simon almost got to the end without needing the secret. It popped up right near the end and for some reason it felt even more special

[@geminimaxxim]

This is definitely one of the "Simon, do your sudoku!" puzzles of all time

[@ronjohnson6916]

Which is funny in the sense that the first Simon video I watched was a solve of a classic sudoku titled something like how to solve a hard sudoku. And delved into things like bent triples. He has the skills to be a good straight sudoku solver, but when he's thinking about logical constraints he simply doesn't scan as much as most of us.

[@erickhernandezcrispin9671]

@@ronjohnson6916 well yeah those are different ways of thinking and it requires a little rewire and in these puzzles he almost avoid to look for normal sudoku clues since usually there's none

[@engunneer]

I was sort of hoping for "That's two in the corner", since it would have been "Close Enough". Fun concept from IcyFruit.

[@justinwlacy]

What this puzzle was really missing was a single-cell cage that summed to 0. I know it would have changed the logic for the solve, but it would have been a great visual gag.

[@six_5000]

First I broke the puzzle in 30 minutes. Then I broke the puzzle in 90 minutes. Then I solved the puzzle in 40 minutes. There goes my entire day

[@toms7114]

@57:00 Simon "I don't know how to resolve this" clicks on the cell that resolves everything that with previous deductions he already knows that it can only be a 7 out of the 3 choices available that unwinds the whole puzzle. Which I've been telling Simon that it could not be a 9 for 20 minutes, and once the rest of the 20 cage was filed could only be a 7.

[@RichSmith77]

He worked out there was no 9 in the 20 cage once over, but then pencil-marked a 9 in r7c7. It stopped him noticing there was only one place for a 9 in c7 for a long time too.

[@janerobson2297]

This really distracted me for so long. But the elation I felt when he finally spotted it almost made up for it.😊

[@Mephistahpheles]

@57:58 "Um...let's try..." and incidentally highlights THE cell that causes the whole grid to collapse....if he looked at it. Love it!

[@enericm]

I figured this was something someone else noticed.

[@whitetiger1518]

Came back from holiday to discover that my boiler has leaked everywhere in my flat. Adrenaline overload. Searched through my stash of Simon videos for a nice long one that I haven't watched yet . Bobbins therapy has helped. I can now face the clean up a bit better . Thank you so much Simon and Mark, this channel keeps me sane!

[@RichSmith77]

@39:50 "There's no 9 in this [20] cage" Barely a minute later (@41:00), pencilmarks a 9 into r7c7, which stays there for the next 20 minutes.

[@hotwheelsnholdem4873]

thanks for the birthday shoutout Simon. the secret 45, still feel young at heart.

[@RichardDamon]

As an Engineer, the comment is that often close is good enough,

[@guilhermecosta5458]

Imagine What a lovely reaction would be if those kids could understand english and hear Simon say they are one of his favorite people ❤️

[@craftsmanwoodturner]

Only one thing for it, Simon: Swedish subtitles on all your videos from now on!

[@krtwood]

Maverick was doing his best to stay Close Enough to be heard for the entire solve.

[@angec9908]

I’m with the Swedish kids about your videos. I speak English and I still done understand what you’re saying but I’m fascinated how you solve empty sudoku boards.

[@henk-ottolimburg7947]

I really liked this puzzle. every step was difficult, but there was constant movement and you never got really stuck along the way.

[@AleksandrYgA]

32:48 for me. Great new idea with the rounded totals

[@tuomatz]

16:40 Simon sharing The Secret about 12-cages brings tears to my eyes

[@johncox7169]

Simon: "This T 20+5 cage can't have 9 in it" less than 30 seconds later, Simon pencil marks a 9 into the T 20+5 cage :D

[@zaclewis1869]

Simon is trolling me on purpose! 😂 I'm screaming, "Look at the 20 cage in box 8!" Finally at 58:00 he says, "Let's try..." while clicking on cell R7C7 and I think, "YES! There we go!" He then jumps to another part of the grid. 😭😆

[@chocolateboy300]

I finished in 112 minutes. This was difficult, but I made steady progress throughout the puzzle, so it didn't feel like a slog. As soon as I focused on where 123s go in the puzzle, it made my progress flow. I really liked this ruleset. I even colored the different sets based on how far away they were from their shown total. Great Puzzle!

[@phuybrechts6875]

Scan , Simon , SCAN 😁🫤

[@emilywilliams3237]

A couple of days late, but I'm so glad I came back for this one. Very interesting! Thanks, Simon, for the video, and for all that you do on the channel.

[@IronLucario2012]

Amazing to see just how different of a path we can take to the same solution - my solve in 56 mins 48 secs ended up using the 15 cage as the final disambiguator at the end, just for an example. I approached it by colouring the cages based on how they could relate to their stated totals, from -2 to +2, which helped figure out the 20-cage faster than Simon managed here.

[@lavarel]

Same! Last disambiguation is that top 15. I first thought this was high-low puzzle. Then it clicks that since we care more about difference of two, i should make it high-mid-low puzzle. So i fill out the 123s, 456s, and 789,

[@mstmar]

its interesting that me and simon used the same clues, but in a different order to break into the puzzle. starting with the grid at 18:00, we can see that the 20 cage in box 8 and 9 can only contain at most 2 low (123) digits by sudoku. can it contain any less than that? no because 1+4+5+6+7=23. so it has to contain exactly 2 low digits which have to go in col 7. this means we can only have at most 1 low digit in r2c7 and r3c7. as simon said, we need at least 2 low digits in box 3 outside of cages, so r3c8 must be low. Where is that digit in box 1? not in it's row nor in the 30 cage, so it has to be in either r1c3 or r2c3. but we already have 2 1s and 2 2s in col 2 and 3, so we can't add another, forcing it to be a 3. this gives us the 3 in box 7, and no 3 in the 10 cage in box 1 and 4, forcing it to be a 1245. with a bit of sudoku, we end up at 39:02 in the video.

[@MariaVlasiou]

Great timing!

[@oneeyedman4431]

It amazes me that I always enjoy your videos and watch them to the end even when I struggle to follow the logic. That is a talent. PS, love the long videos 😊

[@anaayoung9142]

I needed some tips but it was still a doable puzzle! Thank you! 😊

[@piarittersporn]

Beautiful and funny puzzle. Not too difficult.

[@Kinada]

Brilliant puzzle. It felt really hard all the up until it wasn't. I certainly spent most of my time at the mid point looking for the restrictions then one of them cascaded though all the work I had done and it was finished. Loved it.

[@lucasmandato4910]

I genuinely cried due to the email, what a beautiful thing...

[@DjurslandsEfterskole]

156 minutes! Enjoyed it

[@rileylewis5179]

Been loving your videos. AND I’m an engineer! What a treat!

[@kpopthinker3268]

that story was so lovely

[@laincoubert7236]

what a neat puzzle. loved how everything was constrained to the 123s, thankfully i realized that pretty fast. 40 minutes for me

[@Gonzalo_Garcia_]

24:33 for me. Great puzzle, very fun to solve!

[@NightChime]

I had a good extra 17 minutes of amusement watching Simon neglect (using) the 3/5 pair in box 5. Maybe if it pointed to a corner he'd have sooner sorted out whether or not it put a 3 there.

[@MattYDdraig]

33:10 Love the concept and the execution was every bit as good. Great puzzle.

[@grahamania]

00:55:56 for me. Engineer or not (I am), the puzzle is worth loving! Kind comment.

[@srwapo]

86:30, but as an engineer, I totally used a calculator and looked up "information" in the video when I got stuck a handful of times. I feel like this would have worked better for me if, in addition to the values being rounded to the nearest 5, I could "approximately" use the digits 1-9 "usually" once each.

[@angec9908]

Not understanding anything you say I was screaming about that 7 in the 20 cage 😂

[@n0bl3hunt3r]

A very tasty shouting at Simon about missing sudoku and then he pulls out a cage clue that I’d completely missing.

[@zoltankalovics7910]

39:00 an even easier way to see that the bottom 2 cells of the 20 cage are from 123 is that if they aren't, then that means that out of the 5 cells in the cage, 4 must be 3+, which is at least 4+5+6+7=22 which is already the limit of the entire cage, so adding +1 as the 5th cell breaks it

[@Yttria]

Fairly challenging. Finished in 88:13.

[@ingvarsuigin609]

I also live near an airplain route, so I can listen to my planes while also listening to your planes!

[@SuperPlienie]

Thank you so much for the birthday shout out ❤❤🎉🎉

[@sheazellweger5450]

wow, this took me over 2 hours of off and on pondering but I liked it quite a bit as a rule set

[@bluerizlagirl]

It's legitimate in engineering to make approximations -- such as g = 10 m.s⁻², or the striking voltage of an LED is negligible compared to the mains, and of course the small-angle approximation that sin θ = tan θ = θ -- sometimes we even used things as outrageous as 7*7=50 or 3*3=10, in the days before calculators! -- as long as you don't rely _too_ heavily on them. (Estimating heater powers as multiples of 70 watts is also a common one; since 70 watts * 1 minute will make 1 litre of water 1 degree hotter.) Often, you really just want an upper or lower bound anyway, such as "How much is this thing going to move when people are walking on it?" or "Is this thing going to get too hot to touch?" You can always do a more accurate calculation later -- or see straight away that you're "Ms. Blackman concealing 20? Sounds like an exercise in futility to me! (2, 1, 6, 2, 7)" and rethink an obviously lousy design before wasting too much time with it. Numerical approximations can also yield surprisingly accurate solutions to differential equations -- and sometimes, more quickly than doing it "properly", given that some functions are very much not fun to integrate. The smaller you make the steps, the better the approximation you get.

[@emirfassad3974]

Sometimes I just want to drag Simon's cursor. 😸

[@Raven-Creations]

You missed a huge trick early on when considering the 5 cage in box 9. It sees all of the 20 cage, so together they have to be at least 28, but by the rules can be at most 29. Therefore they are 1-6 and either 7 or 8. This means the two 123s in R7 in box 7 must go in the bottom of the 20 cage. There's one 456 in the 5 cage, and two 456s in the horizontal arm of the 20 cage, as well as the 78. R7C4 is 789. The lows in the 20 cage combining with the lows placed in R3 mean that R2C7 is dark green, and R3C8=3. This makes R3C7 a 45, which is the same as the one in R4C3. In C9, 3 can only go in R4. There's a 12 pair in C8 on box 6, only one of which goes in the cage, so R4C8 is a 123, completing the 123s for the row. If you'd coloured your 3s, 4s, and 5s, you'd have made much quicker progress. You'd have found that 5 has to go in the 15 cage in box 6, which therefore needs an 8, making the 20 cage above it 297, resolving your 12s. @ 49:07 - "I suppose I could pencil-mark it" - if you hadn't put a 9 candidate in R7C7 where you knew it couldn't be, you'd have been able to place 9 in R4C7. @ 60:05 - "So there is a 5 in here" - there's a 35 pair looking at one of those two pencil-marks. The 5 must be in R5C9, with 8 in R6C9. A very entertaining puzzle, with some lovely logic.

[@ericpraline1302]

At first I didn't think I was going to get on with this puzzle, but then I did though I kept having to remember how rounding worked. I did more pencil marking than usual.

[@thatonerisottosimp6791]

yippie!! so excited for the videooo

[@psiphiorg]

This one was a bit perplexing to me. Although I am an engineer (of the software variety), I don't much care for rounding by that much. Rounded to the nearest five minutes, my time was 40:00, and I was solver number 2870. (But actually, they were 40:43 and 2872, respectively.)

[@DarrenNakamura]

I've spent about an hour on this but haven't really broken into anything yet. I think I have to give in and watch the video without solving it myself.

[@frankjiang1857]

Finished in 31:55. Not really sure why engineers would love this, but I'm an engineer and I do love this. Interesting ruleset with the rounding killer cages. It seemed fairly straightforward, but maybe that's just my engineering brain talking..... Fun puzzle!

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

23:53 for me. thanks for the birthday, HIJ is pronounced in spanish... like I-J where I is pronounced like the "i" in Big and J is pronounced hard like the H in hard (but rougher). Sch stands for my actual last name that i dont think i should share, but its german. PD: listening to your british voice is a nice start to learning voiced english for non-native speakers, same applies for Mark.

[@Gonzalo_Garcia_]

Happy birthday!

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

@@Gonzalo_Garcia_ thanks

[@alltradejack]

I am flabbergasted. I thought Simon knew Maverick personally but did not want to reveal their true name. Today, I find out he was imparting a facetious reference to a total stranger, all along.

[@adinom687]

As an engineering student, I was both offended and entertained by this puzzle.

[@FlamingZombie567]

This is probably a unique experience within the field of engineering, but as a nuclear engineering student, most of my homework has to be to at least 6 digits of precision. We even have to know Avogadro's number to 8 digits rather than the usual 4.

[@ezra7088]

Jesus this took me soooooo long, I can't even

[@awilliams1701]

I just noticed that box 1 is sharp and the others are blurry. Weird

[@giladooshlon]

Very nice puzzle. 39 minutes here.

[@michaels4340]

8:30 thanks Simon, was wondering whether eg 7 could round to 10

[@michaels4340]

actually maybe i'll just watch the video on this one...

[@shetrick8761]

You have my attention.

[@jansteyaert1]

Sometimes... I have to believe Simon when he says he doesn't want to do sudoku in a sudoku puzzle. "I don't know how to do this", has a digit staring at a cell that only has 2 candidates.

[@angec9908]

Maverick always waiting until you start recording 😂

[@compdude551]

The rounding makes this harder

[@mr_waffles_the_dog]

Oh yay, I was going to recommend this because I saw it the other day, and I could get a feeling for how to approach it, but beyond some basic deductions couldn't make any real progress. Looking forward to finding what "blindingly obvious" Simon will be apologising for while I'm sitting there going "I think numbers go in the grid somewhere"

[@mr_waffles_the_dog]

The answer is that I was being a muppet - being so stuck with sudoku digits 1-5 and 5-9, 3 and 7 become "middle digits" of the 5 options, except of course the position of a digit in the set of sudoku digits has literally nothing to do with whether something is a multiple 5. i.e 7 "could" "round to 5 or 9", but that's completely irrelevant as where comparing 5 and 10 not 5 and 9. I swear I can count.

[@myfyrmadocjones]

Actuaries might hate it! 😀😀😀

[@AngelWedge]

38:57 … wondering where the T shape is going. My logic there is that if the 20 cage doesn't contain green or 3, its minimum value is 1+4+5+6+7 = 23… which doesn't round down to 20. So the 3 must be there.

[@bobblebardsley]

I wonder how accurate the auto-generated KZbin captions would be once auto-translated into Swedish? (One of the options via the cog icon at the bottom-right of the video, I think.) What is the Swedish for 'bobbins' anyway?? 😜

[@brachypelmasmith]

quite above my paygrade but a very interesting idea

[@jaymuse127]

1. This story was awesome. 2. Maverick did the fly by in both. The second movie was well done

[@trace_tomorrow]

Software engineer here. A related adage is there are no solutions, only tradeoffs. Which is funny to me in the context of logic puzzles.

[@StephenMarkTurner]

Elec. Eng. '84, Waterloo. Do students today still boo when the prof mentions Taylor Series?

[@awilliams1701]

I got green is 1 because you can only leave out up to 9 in box 3. You already had 3 and 5. So it can't be 2.

[@yaelvercammer5468]

As an engineer I couldn't pass on this one, even if I never managed to solve 1h+ videos... But I DID IT 02:44:40

[@biaberg3448]

Sofias letter was so beautiful. ❤ from Norway.

[@smet145]

Yes! Hoping she appears in the comments so we can thank her 😊

[@sofiaolsson1530]

​@@smet145 I have appeared!

[@smet145]

@@sofiaolsson1530 Hi Sofia 😃. That was such a lovely letter. It really adds to the lovely community on this channel to hear stories like that. Love from the UK ❤️

[@nickhamel2021]

Since engineers tell me sin(x) = x, I am sure they love to round.

[@xerodeus2337]

I don't know what it is but I'm learning more and more I'm not a fan of "lying" puzzles. I found 2 digits but this hurts my brain lol

[@LednacekZ]

42:19 for me. not an engineer, but enjoyed it anyhow.

[@tremkl]

Did someone say 2 hour Icy Fruit video? 👂

[@BigAsciiHappyStar]

The poor 10 cage in box 8, I don’t think it ever got used?

[@JPgreekgaming]

Never apologise for Maverick, we like Maverick!

[@chipsounder4633]

42 minutes in... Look and try and make row 7 column 7 a 6... That doesn't work as it will force the 789 into the 5 cage and that breaks so green is 1.

[@CuZZiC4n]

send this to rce

[@strawberrymilk3695]

24:00 simon! You could place the 4 to top right there 😢

[@RichSmith77]

How?

[@strawberrymilk3695]

@@RichSmith77my bad, turns out i did it by accident and lucky to be correct 😂

[@krampus91]

This was the furst icyfruit puzzle I could not solve on my own, but I still love the logic behind it.

[@KaiSaNara]

Sudoku discord server where

[@kiminclw1664]

😃

[@TurquoizeGoldscraper]

67:26 for me.

[@Paolo_De_Leva]

Actually, I am an engineer but I did not love this. Too hard for me to solve it. Luckily, Simon showed me how to do it. Anyway, I can see it is an outstandingly smart construction, and the ruleset is innovative and interesting. I hope someone will use (or has already used) this ruleset to build a more approachable puzzle.

[@Kirbyfan87827]

9:51 Simon has barely started his solve and he's already lost me. He doesn't explain how the minimum for the cages are 28 and two 8s, when the minimum a four cell cage and a two cell cage can add to is typically 10 and 3, respectively... Wait, I just got it. Any less than 28 would round down to 25 or lower, and the same principle applies to 8. Still wish he would have explained that.

[@sarahlowes1501]

Simon explained that the 30 cage in box 5 had to be between 28 & 32 in the introduction at about the minute mark.

[@Kirbyfan87827]

@@sarahlowes1501 That would explain it. I usually skip to the rules section of the video.

[@boblambert8985]

From 53:33 Row 7 column 7 has to be a 7. I'm sure Simon does this stuff deliberately to get clicks and comments! To be honest, I probably wouldn't have got to that stage...

[@peaoui165]

I'm an engineer and I hate this puzzle. We deal in precision... rounding is a sin against engineering