# What is the Greatest Common Factor of 10 and 21?

Greatest common factor (GCF) of 10 and 21 is 1.

GCF(10,21) = 1

We will now calculate the prime factors of 10 and 21, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 10 and 21.

GCF Calculator and
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## How to find the GCF of 10 and 21?

We will first find the prime factorization of 10 and 21. After we will calculate the factors of 10 and 21 and find the biggest common factor number .

### Step-1: Prime Factorization of 10

Prime factors of 10 are 2, 5. Prime factorization of 10 in exponential form is:

10 = 21 × 51

### Step-2: Prime Factorization of 21

Prime factors of 21 are 3, 7. Prime factorization of 21 in exponential form is:

21 = 31 × 71

### Step-3: Factors of 10

List of positive integer factors of 10 that divides 10 without a remainder.

1, 2, 5

### Step-4: Factors of 21

List of positive integer factors of 21 that divides 10 without a remainder.

1, 3, 7

#### Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 10 and 21. The biggest common factor number is the GCF number.
So the greatest common factor 10 and 21 is 1.

Also check out the Least Common Multiple of 10 and 21