A rectangular sheet of paper measures 12 centimetres by 8 centimetres. A rectangular hole 4 centimetres by 3 centimetres is cut out of the middle of it. Enter the number of square centimetres of paper that remain.

توضیح

Multiplying 12 by 8 measures the whole sheet, and 4 by 3 measures the hole, so the paper left over is 96 minus 12. Entering 96 ignores the cut altogether, while shrinking the sides to 8 by 5 first treats the hole as though it had been sliced off two complete edges instead of taken from the middle.