# What is the Greatest Common Factor of 66 and 81?

Greatest common factor (GCF) of 66 and 81 is 3.

GCF(66,81) = 3

We will now calculate the prime factors of 66 and 81, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 66 and 81.

GCF Calculator and
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## How to find the GCF of 66 and 81?

We will first find the prime factorization of 66 and 81. After we will calculate the factors of 66 and 81 and find the biggest common factor number .

### Step-1: 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-2: Prime Factorization of 81

Prime factors of 81 are 3. Prime factorization of 81 in exponential form is:

81 = 34

### Step-3: Factors of 66

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

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

### Step-4: Factors of 81

List of positive integer factors of 81 that divides 66 without a remainder.

1, 3, 9, 27

#### Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 66 and 81. The biggest common factor number is the GCF number.
So the greatest common factor 66 and 81 is 3.

Also check out the Least Common Multiple of 66 and 81