It's the remainder operator. It's the value that you would get after long division and getting a remainder. So:
7 % 3 = 1
6 % 3 = 0 (no remainder from 6 / 3)
5 % 3 = 2
4 % 3 = 1
3 % 3 = 0
2 % 3 = 2
1 % 3 = 1
0 % 3 = 0
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I'll make something real quick to show how it's used to find cellX.
7 % 3 = 1
6 % 3 = 0 (no remainder from 6 / 3)
5 % 3 = 2
4 % 3 = 1
3 % 3 = 0
2 % 3 = 2
1 % 3 = 1
0 % 3 = 0
___
I'll make something real quick to show how it's used to find cellX.
![[Image: QUmE6.gif]](http://i.imgur.com/QUmE6.gif)