# What is the GCF of 21 and 10?

GCF (Greatest Common Factor) of 21 and 10 is the largest possible number which divides both 21 and 10 exactly.

## Answer: GCF of 21 and 10 is 1

Let's find the GCF of 21 and 10

## Explanation:

The greatest common factor of two numbers x and y is the greatest number that divides x and y leaving the remainder as 0

## Methods to Find GCF of 21 and 10

### GCF of 21 and 10 by Listing the Common Factors

Factors of 21: 1, 3, 7, 21

Factors of 10: 1, 2, 5, 10

There is only one common factor of 21 and 10, that is, 1

So, GCF(21, 10) = 1

### GCF of 21 and 10 by Long Division

- Step 1: Divide 21 by 10 and check the remainder.
- Step 2: Make the remainder 1 as the new divisor and the previous divisor 10 is the dividend and perform the long division again. The last divisor is our GCF.
- Step 3: Continue till you get the remainder as 0

The answer to GCF of 21 and 10 is the same in this method too, that is, GCF of 21 and 10 is 1