2

Part of 1989 Chile National Olympiad

Problems(1)

no of squares in mxn rectangle, crossed by diagonal (Chile NMO 1989 P2)

Source:

We have a rectangle with integer sides

m, n

that is subdivided into

mn

squares of side

1

. Find the number of little squares that are crossed by the diagonal (without counting those that are touched only in one vertex)

geometryrectanglecombinatorics