# GCD | Greatest Common Divisor

GCD or Greatest Common Divisor is the largest number that is divisible in a set of numbers.

For example: With 4 and 8 the GCD= 4, or 4 is the largest number that you can divide into both 4 and 8.

Let's look at an easy way to figure out the greatest common divisor for any set of numbers.

Example: Find the GCD of 12 and 40.

First, we need to find the prime numbers that multiply together to give us each number.

12 = 2 * 2 * 3 (these are the prime numbers that multiplied together equal 12)

40 = 2 * 2 * 2 * 5 (these are the prime numbers that multiplied together equal 40)

Next, we find the numbers that both 12 and 40 have in common. As you can tell they both have two 2's in common so we multiply those numbers together 2 * 2 and the GCD is 4.

Watch the math video below for a detailed explanation!

### Practice Math Problems

1. What is the GCD of 12 and 36?
2. What is the GCD of 45 and 33?
3. What is the GCD of 4 and 66?
4. What is the GCD of 54 and 14?
5. What is the GCD of 3 and 5?
6. What is the GCD of 64 and 22?
7. What is the GCD of 10 and 55?
8. What is the GCD of 8, 12 and 36?
9. What is the GCD of 14, 18, 20?
10. What is the GCD of 15, 36, 72?