Question

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?

Answer 1

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

Answer 2

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

Answer 3

oh

Answer 4

use Euler Function

Answer 5

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