What is GCF for 9 and 13?

2 Answers
Nov 3, 2016

GCF of 99 and 1313 is 11.

Explanation:

The factors of 99 are 3xx33×3, and

as 1313 is a prime number, its only factor is 1313.

Note that there are no common factors between them.

Such numbers are called coprimes or relatively primes.

GCF of such numbers is always 11.

Nov 4, 2016

So GCF (greatest common factor) is 1

Explanation:

Using prime numbers as factors: also including 1

color(blue)(ul("Very important fact;")" 1 is not a prime numbers")

color(brown)("The only factors of a prime number is 1 and the number itself")

color(white)(1)9->color(red)(1)xx3xx3
13->color(red)(1)color(white)(xx3xx3)xx13color(brown)( larr" Thus 13 is a prime number")

The only common factor is 1

So GCF (greatest common factor) is 1