kings problem

chess king

The kings problem is the problem of determining how many non-attacking chess kings, K(n), can be placed on an n × n chessboard. For n = 8, the solution is 16. The general solution is K(n) = ¼n 2 if n is even and K(n) = ¼(n + 1)2 if n is odd. The minimum number of kings needed to attack or occupy all squares on an 8 × 8 chessboard is nine.