Y by Adventure10
In each of the squares of a chessboard an arbitrary integer is written. A king starts to move on the board. Whenever the king moves to some square, the number in that square is increased by
. Is it always possible to make the numbers on the chessboard:
(a) all even;
(b) all divisible by
;
(c) all equal?

(a) all even;
(b) all divisible by

(c) all equal?