A matchstick is 1 unit. The area of the 2×2 square is 4 square units. When 2 matchsticks are moved as is in the Example, the area of the new shape is 3 square units.
What is the minimum number of matchsticks to be moved in the 2×2 square in order to get a shape of the 2 square units?
No damaging, loose ends or overlapping of the matchsticks is allowed.
It’s enough to move 3 matchsticks. The approach can be described as “folding” of the frame. Folding three matchsticks (shown as black) inside the square reduces its area by two square units – the shaded right triangle equals the area of one square unit.