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MathNet 2013 Question 68

Math Olympiad Vault · MathNet 2013

Question 68

Define a size-$n$ tromino to be the shape you get when you remove one quadrant from a $2n \times 2n$ square. In the figure below, a size-1 tromino is on the left and a size-2 tromino is on the right.

Question illustration

We say that a shape can be tiled with size-1 trominos if we can cover the entire area of the shape—and no excess area—with non-overlapping size-1 trominos. For example, a $2 \times 3$ rectangle can be tiled with size-1 trominos as shown below, but a $3 \times 3$ square cannot be tiled with size-1 trominos.

Question illustration

a) Can a size-5 tromino be tiled by size-1 trominos?

b) Can a size-2013 tromino be tiled by size-1 trominos?

Justify your answers.