# Math Help - Decimal Expansion

1. ## Decimal Expansion

Suppose that n>1, and the decimal expansion of 1/n has a purely repeating deciaml expansion with period n-1. Prove that n is prime.

Very lost on how to do this one.

2. Originally Posted by mndi1105
Suppose that n>1, and the decimal expansion of 1/n has a purely repeating deciaml expansion with period n-1. Prove that n is prime.

Very lost on how to do this one.
Try this.