MathDB

4

Part of 2014 Bulgaria JBMO TST

Problems(1)

Chessboard tromino tiling

Source:

5/18/2015
Removing a unit square from a 2×22\times 2 square we get a piece called L-tromino. From the fourth line of a 7×77 \times 7 cheesboard some unit squares have been removed. The resulting chessboard is cut in L-trominos. Determine the number and location of the removed squares.
combinatorics