# What is the GCF of 15 and 28?

GCF of two numbers 15 and 28 is the largest possible number which divides both the numbers exactly.

## Answer: GCF of 15 and 28 is 1

Let us see how to find the GCF of 15 and 28.

## Explanation:

The greatest common factor of two numbers is the largest possible number which divides both the numbers exactly without any remainder.

We can find the GCF of the numbers in many ways, the commonly used methods are listed below.

## Methods to Find GCF of 15 and 28

- Listing the common factors
- Long division

### Method 1: GCF of 15 and 28 by Prime Factorization

In this method, we represent 15 and 28 as a product of its prime numbers

Prime factorization of 15 is 3 × 5

Prime factorization of 28 is 2 × 2 × 7

There is no common factor except 1. So, GCF is 1

### Method 2: GCF of 15 and 28 by Listing the Common Factors

In this process, we list all the factors of 15 and 28, then identify the common factors.

The highest among the common factors is the GCF of 15 and 28.

The factors of 15 are 1, 3, 5, 15

The factors of 28 are 1, 2, 4, 7, 14, 28

1 is the only common factors of 15 and 28

So, GCF of 15 and 28 is 1

Irrespective of the method, the GCF(15,28) is the same.