The greatest common factor is the largest number that both 30 and 12 can be divided by (without giving any remainder).

The number you are looking for in this case is 6 because:

30/6 = 5

12/6 = 2

There isn't a number larger than 6 that goes into 30 and 12, so 6 is the largest common factor.

The greatest common factor is also know as the greatest common divisor or the highest common factor.

30 and 12

1x30

2x15

3x10

5x6

Factors of 30=( 1,2,3,5,6,15,30)

1 x 12

2 x 6

3 x 4

Factors of 60=( 1,2,3,4,6,12)

Common Factors of 12 and 30 =( 1,2,3,5,6)

The greatest Common Factors of 30 and 12 =6

You have to take the highest factor of your smallest number, which is 12. The number 12 can be divided by 1, 2, 3, 4, 6, and 12, but out of those factors, only 1, 2, 3, and 6 divide evenly into 30. So the highest, common factor is 6.

...30 and 12

Factors of 30={ 1,2,3,5,6,15,30}

Factors of 60={ 1,2,3,4,6,12}

Common Factors of 12 and 30 ={ 1,2,3,5,6}

The greatest Common Factors of 30 and 12 =6

30 and 12?

2 30 12

3 15 6

5 3

since 2 and 3 are numbers that divides both 30 and 12 without leaving a remainder.

Greatest common factor = 2*3= 6

6

The prime factors of 30 are 2 x 3 x 5

The prime factors of 12 are 2 x 2 x 3.

The common factors are 2 and 3 (one of each), so the GCF is 2 x 3 = 6.