What is the Greatest Common Factor of 15 and 18?
Greatest common factor (GCF) of 15 and 18 is 3.
GCF(15,18) = 3
We will now calculate the prime factors of 15 and 18, than find the greatest common factor (greatest common divisor (gcd)) of the numbers by matching the biggest common factor of 15 and 18.
How to find the GCF of 15 and 18?
We will first find the prime factorization of 15 and 18. After we will calculate the factors of 15 and 18 and find the biggest common factor number .
Step-1: Prime Factorization of 15
Prime factors of 15 are 3, 5. Prime factorization of 15 in exponential form is:
15 = 31 × 51
Step-2: Prime Factorization of 18
Prime factors of 18 are 2, 3. Prime factorization of 18 in exponential form is:
18 = 21 × 32
Step-3: Factors of 15
List of positive integer factors of 15 that divides 15 without a remainder.
1, 3, 5
Step-4: Factors of 18
List of positive integer factors of 18 that divides 15 without a remainder.
1, 2, 3, 6, 9
Final Step: Biggest Common Factor Number
We found the factors and prime factorization of 15 and 18. The biggest common factor number is the GCF number.
So the greatest common factor 15 and 18 is 3.
Also check out the Least Common Multiple of 15 and 18