May 2004

## Square tactics

How many squares are there on a chessboard? (In total - we're not asking you just to count the 64 single black and white squares!)

If you are stumped by last issue's puzzle, here is the solution.

For some challenging mathematical puzzles, see the NRICH puzzles from this month or last month.

## Comments

## 204

1 + 4 + 9 + 16 + 25 + 36 + 49 + 64=204

3 5 7 9 11 13 15 the difference between the numbers in the lines over

2 2 2 2 2 2 the difference between the numbers in the lines over

I only found out the numbers 1,4 and 9, and on the I used my knowledge about the difference on the numbers.

## Chessboard Answer

There are many more different-sized squares on the chessboard. Therefore, there are actually 64 + 49 + 36 + 25 + 16 + 9 + 4 + 1 squares on a chessboard! (in total 204).