Problem

Source: St. Petersburg MO 2001, 10th grade P4

Tags: combinatorics, Tiling, board, table, Coloring, rectangle, domino



Rectangles 1×20, 1×19, ..., 1×1 were cut out of 20×20 table. Prove that from the remaining part of the table 36 1×2 dominos can be cut Proposed by S. Berlov