Mahima writes all the numbers from 1-100. Prachi then writes out all the numbers that are relatively prime to and lower than the numbers that Mahima wrote. How many numbers did Prachi write?

Question

anonymous · Answer

Its like asking how many prime numbers are there between 1 - 100 right?

anonymous · Answer

relatively prime means that the 2 numbers share no common factor other than 1

anonymous · Answer

oh

anonymous · Answer

use Euler Function

anonymous · Answer

$$\phi(x)=x \times \prod_{p is a prime, p|x}^{}1/(p-1)$$