This new type of logic puzzle is wildly fun

What is the code lock pin? Can you crack the code for the 3x3 grid?

0:00 puzzle 1
4:37 puzzle 2

Code lock pin puzzle
Grid based mastermind logic puzzle

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If you purchase through these links, I may be compensated for purchases made on Amazon. As an Amazon Associate I earn from qualifying purchases. This does not affect the price you pay.

Book ratings are from January 2023.

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Mind Your Decisions: Five Book Compilation
A collection of 5 books:
"The Joy of Game Theory" rated 4.3/5 stars on 290 reviews
"The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" rated 4.1/5 stars on 33 reviews
"40 Paradoxes in Logic, Probability, and Game Theory" rated 4.2/5 stars on 54 reviews
"The Best Mental Math Tricks" rated 4.3/5 stars on 116 reviews
"Multiply Numbers By Drawing Lines" rated 4.4/5 stars on 37 reviews

Mind Your Puzzles: Collection Of Volumes 1 To 3
A collection of 3 books:
"Math Puzzles Volume 1" rated 4.4/5 stars on 112 reviews
"Math Puzzles Volume 2" rated 4.2/5 stars on 33 reviews
"Math Puzzles Volume 3" rated 4.2/5 stars on 29 reviews

2017 Shorty Awards Nominee. Mind Your Decisions was nominated in the STEM category (Science, Technology, Engineering, and Math) along with eventual winner Bill Nye; finalists Adam Savage, Dr. Sandra Lee, Simone Giertz, Tim Peake, Unbox Therapy; and other nominees Elon Musk, Gizmoslip, Hope Jahren, Life Noggin, and Nerdwriter.

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[AradijePresveti]

Guess I'm a genius then and surrounded by a lot of geniuses somehow.

[jj]

I was absolutely stumped by the first question. I saw that there were 2 possible codes. Then I unpaused and realized I had not gotten the final clue yet.

[zektarius]

Solved both puzzles in 1 seating, about 20 minutes, without writing anything out; the mental checking process is quite a brain workout!

[snarkk]

these puzzles are rly simple, i solved them rly quickly, theres no way that every person who can solve this is a genius

[ThatGuy-jjkz]

The second puzzle gave me sudoku vibes and took a while to solve on my own

[evan]

I haven’t been doing anything after high school for 2 years, and, quite frankly, I’ve been struggling. You’re videos seem to be helping me get back into the swing of things. Thank you for making AND THEN POSTING this educational content, Presh.

[WilliamWen]

yay. I must be a genius? or just someone who plays sudoku a lot...

[steelcitytbirds]

@4:35 - One of the few times I've been both correct and quick on one of your puzzles.

[CarlosISoares]

don't know if is faster, but I did 9 matrices - 1 for each number - and start eliminating one by one in each square.

[vmadhavan]

Please do more of these logic puzzles !!!

[qqma]

Thumbnail is 3841. Why did I do the thumbnail one lmao 😂

[peterkwan]

For the first puzzle, I think 1234 is a better clue to eliminate 1 and 2 in one go, with only 7 left over.

[jplayers]

I'm so bad with these kind of puzzles but I decided to try and after writing up the list of suspects I was easy to just discard the ones that aren't part of the password and it also helps you to remind that the 7 exists even if is not written in the clues.

I'm currently training to improve in strategy games and you videos are helping me a lot, thank you very much.

[JasonEwton]

2nd puzzle is made much simpler if you use WFC (Wave Function Collapse) algorithm. These were fun. Thanks for the upload!

[trainererich]

In the first puzzle, after using the 3rd and 4th clues (5, 8, 9, 0) and (3, 4, 5, 6) to figure out 3 of the numbers and eliminate 4, the first clue (1, 2, 3, 4) gets you to the 4 correct numbers, instead of needing to use clues 4 and 5.

[geoninja]

Sneaky.... I solved the mastermind puzzle on paper, then checked it with my trusty little C code I wrote to make/check these.... thanks!

[turehansson]

thank you, these problems were fun. I always enjoy when you put out your puzzle videos. 😃

[dattaprasadgodbole]

I didn't solve these questions in minutes, like everybody here. But I did solve it and am happy for that. Thanks, Presh, for these puzzles.

[chrismoule]

I always use a matrix to solve puzzles like Puzzle 1, as a matrix allows you to eliminate possibilities once positions are known - i.e., every time you put a tick in a matrix, you can put crosses in every other location in the same row and the same column.

In this case the matrix is a very simple single-block matrix: possible numbers vertical in Rows, and possible positions across in Columns.

So Clue 3 enable you to put crosses in all columns in the rows for numbers 5, 8, 9 & 0.

Similarly, Clue 1 enables you to put a cross at Row 1, Col 1, also a cross at R2C2, and at R3C3, and at R4C4. This is because the numbers may be right but they don't go in those columns.

Taking Clue 2, you already have crosses in all columns for Row 5, so the other 3 numbers must be correct, but as none of them is in the right place you can put crosses in R3C1, R4C2, and R6C4.

Taking Clue 4, you know that the two numbers that are correct must be 3 & 4, from Clue 3, so numbers 2 & 0 [the latter already known] must be wrong, so put for crosses in for Row 2.

Similarly, Clue 5, following Clue 3, tells you that the correct numbers are 4 & 6, so 1 must also be wrong, so put 4 crosses in Row 1. But this clue ALSO tells you that 4 & 6 are in the correct positions. So put a TICK in R4C3 & in R6C1. BUT as this is a matrix, if you have a tick somewhere, there can't be a tick anywhere else in that column or that row - so you can eliminate the rest of Row 4 & Col 3, and Row 6 & Column 1 by putting crosses in. This is extra information.

If you look at your matrix, you now see that there are only 4 locations left unmarked - R3C2, R3C4, R7C3 & R7C4.

But since you now know where the number 4 goes, you can now see that it isn't in the correct place in Clue 4, so it must be the other know number [3] that is correctly placed - so you now put a tick in R3C2. This also means a cross in the rest of Row 4 and Column 2 - leaving only one location unmarked, which is R7C4, so we tick that.


The code is now known

[Misteribel]

I love it that each time you present a very trivial puzzle, you make us all feel like geniuses!