What is The GCF of 15 and 21
Greatest Common Factor of two or more numbers is the largest possible number which divides the given numbers exactly without any remainder.
Answer: GCF of 15 and 21 is 3
We can find the GCF by the following methods
- Prime factorization Method
- Listing the common factors method
- Long division Method
GCF of 15 and 21 by Prime Factorization
Let us represent 15 and 21 as a product of its prime numbers
Prime factorization of 15 is 3 × 5
Prime factorization of 21 is 3 × 7
Common factors = 3
GCF is the product of the factors that are common to each of the given numbers.
GCF is 3
GCF of 15 and 21 by Long Division
- Step 1: Divide 21 by 15 and check the remainder.
- Step 2: Make the remainder of the above step as the divisor and the divisor of the above step as the dividend and perform the long division again.
- Step 3: Continue till you get remainder as 0
You can find the GCF in any of the above methods but the solution will be the same.