What is a rel number?

Answer 1

Relative prime: two integers are termed relative prime if the only common factor between them is 1.

any integer can be broken down into certain multiples of prime numbers. this is called prime factorization. When you prime factorize two integers and the only common number is 1,then the two integers are relative prime.

for ex.

18 = 2 x 3 x 3

35 = 7 x 5

so 18 and 35 are relative primes.

18 = 2 x 3 x 3

21 = 3 x 7

3 is common, so 18 and 21 are not relative prime.
Two integers are said to be relatively prime, or coprime if they share no common positive factor other than 1. For example, the numbers 6 and 35 are relatively prime because they share no common factors.