Question

What is GCF for 9 and 13?

Answer 1

GCF of `9` and `13` is `1`.

Explanation:

The factors of `9` are `3xx3`, and

as `13` is a prime number, its only factor is `13`.

Note that there are no common factors between them.

Such numbers are called coprimes or relatively primes.

GCF of such numbers is always `1`.

Answer 2

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