Find the greatest common factor of 20 and 30.

We can find the greatest common factor of 20 and 30 by finding the factors of the numbers.

Factors of 20 are 1 , 2 , 4 , 5 , 10 , 20

Factors of 30 are 1 , 2 , 3 , 5 , 6 , 10 , 15 , 30

Here, The common factors of 20 and 30 are 1 , 2 , 5 , 10

The greatest number among 1 , 2 , 5 , 10 is 10

Therefore,

The greatest common  factor of 20 and 30 is 10