Having a lot of trouble with this problem as well:(adsbygoogle = window.adsbygoogle || []).push({});

How many integers less than 500 are relatively prime to 500?

I know that when two numbers are relatively prime, that means that the greatest common divisor of those two numbers is 1. But I can't figure out a formula that uses sets in order to calculate this.

If someone could point me in the right direction with this, then it would be greatly appreciated.

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