PlaySudoku.us
Hard · Puzzle #647
4
1
5
8
1
7
2
6
3
6
4
1
1
8
3
7
8
1
6
2
8
5
6
7
3
9
8
9
"Quality is not an act, it is a habit." — Aristotle
"Quality is not an act, it is a habit." — Aristotle
The brain releases dopamine when it solves a puzzle — the same reward chemical triggered by food and exercise.
The brain releases dopamine when it solves a puzzle — the same reward chemical triggered by food and exercise.