# What is the Greatest Common Factor of 90 and 105?

Greatest common factor (GCF) of 90 and 105 is 15.

GCF(90,105) = 15

We will now calculate the prime factors of 90 and 105, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 90 and 105.

GCF Calculator and
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## How to find the GCF of 90 and 105?

We will first find the prime factorization of 90 and 105. After we will calculate the factors of 90 and 105 and find the biggest common factor number .

### Step-1: Prime Factorization of 90

Prime factors of 90 are 2, 3, 5. Prime factorization of 90 in exponential form is:

90 = 21 × 32 × 51

### Step-2: Prime Factorization of 105

Prime factors of 105 are 3, 5, 7. Prime factorization of 105 in exponential form is:

105 = 31 × 51 × 71

### Step-3: Factors of 90

List of positive integer factors of 90 that divides 90 without a remainder.

1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45

### Step-4: Factors of 105

List of positive integer factors of 105 that divides 90 without a remainder.

1, 3, 5, 7, 15, 21, 35

#### Final Step: Biggest Common Factor Number

We found the factors and prime factorization of 90 and 105. The biggest common factor number is the GCF number.
So the greatest common factor 90 and 105 is 15.

Also check out the Least Common Multiple of 90 and 105