## Perimeter Sequence

#### Problem

The first three stages of a sequence are shown.

What is the perimeter of the tenth in the sequence?

#### Solution

By considering the next in the sequence.

It should be clear that the n th in the sequence will be n units tall and n units wide, so there will be 2n horizontal units and 2n vertical units, making the total perimeter 4n. That is, the perimeter of the tenth in the sequence will be 40 units.

Problem ID: 76 (May 2002)     Difficulty: 1 Star

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