PlaySudoku.us
Medium · Puzzle #631
3
1
5
1
6
2
7
8
5
4
9
6
7
9
3
7
4
7
2
8
4
3
8
1
6
9
7
3
8
2
6
2
1
4
7
3
"The book of nature is written in the language of mathematics." — Galileo Galilei
"The book of nature is written in the language of mathematics." — Galileo Galilei
When a box has only two empty cells, you know exactly which two digits fill them.
When a box has only two empty cells, you know exactly which two digits fill them.