# What is the greatest common factor of 42, 63, and 105?

##### 3 Answers

Greatest Common Factor is

#### Explanation:

Factors of

Factors of

Factors of

Common factors are just

Greatest Common Factor is

#### Explanation:

Writing each number as the product of its prime factors is a quick way of finding the HCF and LCM of any number of values.

Therefore the

The greatest common factor of

#### Explanation:

What is the greatest common factor (GCF)?

That is the largest number that will divide into all those given.

To find it, the **smallest prime** numbers should be divided into each one. *Prime* numbers are: **2, 3, 5,** 7, 11, 13, 17, 19.

Looking at

Each division results in the same number, so that is the GCF.