Question

How many numbers less than or equal to 120 are co-prime with 120? (co-prime as in they have no common factors with 120.)

Answer 1

We know that 120 can be factored as 2^3 * 3 * 5, so its totient function value can be found as follows:

φ(120) = φ(2^3) * φ(3) * φ(5)

= 2^2 * 2 * 4

= 16

Therefore, there are 16 numbers less than or equal to 120 that are relatively prime to 120