Question

Find the gcf of 15 and 21

Answer 1

Given: Two numbers- 15 and 21.

Required: To determine the GCF.

Explanation: GCF is the greatest common factor between two or more numbers. We can determine the GCF by prime factorization of 15 and 21 as follows-

`\begin{gathered} 15=3*5 \\ 21=3*7 \end{gathered}`

The greatest common factor among the prime factorization of 15 and 21 is 3.

Hence, the GCF is 3.

Final Answer: The GCF of 15 and 21 is 3.