# What is the Greatest Common Factor of 51 and 66?

Greatest common factor (GCF) of 51 and 66 is 3.

GCF(51,66) = 3

We will now calculate the prime factors of 51 and 66, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 51 and 66.

GCF Calculator and
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## How to find the GCF of 51 and 66?

We will first find the prime factorization of 51 and 66. After we will calculate the factors of 51 and 66 and find the biggest common factor number .

### Step-1: Prime Factorization of 51

Prime factors of 51 are 3, 17. Prime factorization of 51 in exponential form is:

51 = 31 × 171

### Step-2: Prime Factorization of 66

Prime factors of 66 are 2, 3, 11. Prime factorization of 66 in exponential form is:

66 = 21 × 31 × 111

### Step-3: Factors of 51

List of positive integer factors of 51 that divides 51 without a remainder.

1, 3, 17

### Step-4: Factors of 66

List of positive integer factors of 66 that divides 51 without a remainder.

1, 2, 3, 6, 11, 22, 33

#### Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 51 and 66. The biggest common factor number is the GCF number.
So the greatest common factor 51 and 66 is 3.

Also check out the Least Common Multiple of 51 and 66