September 2004

## High roller

What is the probability, if you roll a coin across a chessboard and it comes to rest on the board, that it covers some corner of one of the grid squares?

(You can assume that the diameter of the coin is less than the sidelength of a single square on the chessboard.)

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.