Problem

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

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



Rectangles $1\times20$, $1\times 19$, ..., $1\times 1$ were cut out of $20\times20$ table. Prove that from the remaining part of the table $36$ $1\times2$ dominos can be cut Proposed by S. Berlov