--- title: "Find the Mistake Sudoku #20 | Sudoku Flow" description: "Sudoku puzzle #20: a half-finished board with 58 digits, 22 of them filled in by a player, and one of those is wrong. Find it in five seconds, then check the answer." url: https://sudokuflow.com/puzzles/find-the-mistake-20/ language: en --- [Puzzles](https://sudokuflow.com/puzzles/) / Find the mistake #20 [Find the mistake](https://sudokuflow.com/find-the-mistake/) # Find the mistake #20 One digit on this board breaks the rules. The game is half finished: some digits were printed with the puzzle, the others were filled in by a player. Give yourself five seconds before the video shows it. ## Reading the board ## Where to start This board has 58 digits and 22 of them are blue, so those 22 are the only suspects. The most crowded line is row 3, with 9 digits: a good place to start. [How to find a mistake in Sudoku →](https://sudokuflow.com/guides/find-a-mistake/) ## Try it here Tap the digit you think is wrong. Sudoku board for Find the mistake #20: ```text . . 3 | 5* 8 7 | 4 6 9* 8 . . | 6 4 9* | 1* 2 3* 4 6* 9 | 1 3* 2 | 8* 7 5* ---------+----------+--------- 3 . 8* | 4 2 5 | . 9 . . . 6 | 8* 1 3* | 2 5* 4 . . 4 | 7* 9* 6 | 3 1* 8* ---------+----------+--------- . 3 . | 2* . 8* | 9 4* . . 5* 2 | 9 . 4* | 5 3 1 . . . | 3 . 1 | . 8 . ``` Digits marked * were filled in by a player; the others were printed with the puzzle.
Show the answer It's the blue 5 in row 8, column 2. Row 8 already has a printed 5 (row 8, column 7). A printed digit can't be wrong, so the blue one is. The right digit for that cell is 8.
Video transcript **On screen:** One number is wrong. / How fast did you find it? **Voice:** One number is wrong! Three! Two! One! Right there! How fast did you find it?
How fast did you find it? Tell us under the video. [Watch on YouTube](https://youtube.com/shorts/l1q1DLBeowU)
Embed this puzzle Copy this code to show the puzzle on your own site or blog. It links back here.
## More puzzles [![Find the mistake #19](https://sudokuflow.com/media/puzzles/find-the-mistake-19-en.jpg?v=84b0a41e57)](https://sudokuflow.com/puzzles/find-the-mistake-19/): Find the mistake #19 11 s video [![Find the mistake #18](https://sudokuflow.com/media/puzzles/find-the-mistake-18-en.jpg?v=a349d83936)](https://sudokuflow.com/puzzles/find-the-mistake-18/): Find the mistake #18 11 s video [![Find the mistake #17](https://sudokuflow.com/media/puzzles/find-the-mistake-17-en.jpg?v=da3bba10d9)](https://sudokuflow.com/puzzles/find-the-mistake-17/): Find the mistake #17 11 s video [![Find the mistake #16](https://sudokuflow.com/media/puzzles/find-the-mistake-16-en.jpg?v=1dcd6f49f6)](https://sudokuflow.com/puzzles/find-the-mistake-16/): Find the mistake #16 11 s video ![Sudoku app icon](https://sudokuflow.com/assets/app-icon.png) ## Want more boards like this? We also make a Sudoku app for iPhone, iPad, Mac and Android. There are no ads in it at all, it works offline, and when you ask for a hint it shows you the technique instead of just filling in a number. [App Store iPhone, iPad, Mac](https://apps.apple.com/app/apple-store/id6502922368?pt=125379530&ct=sudokuflow_web&mt=8) [Google Play Android](https://play.google.com/store/apps/details?id=com.rubigogames.sudoku&referrer=utm_source%3Dsudokuflow%26utm_medium%3Dweb%26utm_campaign%3Dsite) Sudoku Flow is made by Rubigo Games, the developer of the Sudoku app recommended on this site.