# GMAT Geometry Practice - Number of Diagonals

Concept: Finding number of diagonals in a polygon.

This GMAT quant practice question is a problem solving question in Geometry. Concept: Finding number of diagonals of an n-sided convex polygon.

#### Question: How many diagonals does a 63-sided convex polygon have?

1. 3780
2. 1890
3. 3843
4. 3906
5. 1953

Video explanation will be added soon

The number of diagonals of an n-sided convex polygon = $$frac{n$n - 3$}{2}$\$
This polygon has 63 sides. Hence, n = 63.

Therefore, number of diagonals = $\frac{63 * 60}{2}\\$ = 1890.

Choice B is the correct answer.

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