How can you find the greatest common factor of two or more numbers?

Answer 1

You need at least two numbers to do that.
Example: 30 and 42
List the factors.
1, 2, 3, 5, 6, 10, 15, 30
1, 2, 3, 6, 7, 14, 21, 42
Select the common factors.
1, 2, 3 and 6.

Answer 2

you start by prime factoring both numbers. Then you compare factors find the ones in common. If you multiply all of them together you will get the greatest common denominator of the two numbers.

Example: Find the greatest common denominator of 305 and 75.

300=5*60=5*3*2*5

75=3*25=3*5*5

the common factors are 5,5 and 3 so the greatest common denominator is 3*5*5=75

Answer 3

To simplify the fraction, I guess. You don't really need the GREATEST common factor; if you find ANY common factor, you can divide top and bottom by that common factor, then continue looking for other common factors.To actually find the greatest common factor of two, here are three methods:

* List all the factors of each number. Look which factors they have in common. Only appropriate for fairly small numbers.

* Split each of the numbers into prime factors. Take all the COMMON factors, and multiply them together. Appropriate for intermediate-sized numbers.

* Use Euclid's algorithm. Appropriate for numbers of any size. As an example, the greatest common factor of 14 and 10 is the same as the greatest common factor of 10 and 4 - where 4 is the remainder of the division, of 14 by 10. Continue until one of the numbers is zero: gcf(10,4) = gcf(4,2) = gcf(2,0), so the greatest common factor is 2.

Answer 4

You'll need at least two numbers.
Example: 30 and 42
Factor them.
2 x 3 x 5 = 30
2 x 3 x 7 = 42
Select the common factors.
2 x 3 = 6, the GCF

Answer 5

You need at least two numbers.

Example: 30 and 42

Factor them.

2 x 3 x 5 = 30

2 x 3 x 7 = 42

Select the common factors.

2 x 3 = 6, the GCF

Answer 6

Example: 30 and 42

Factor them.

2 x 3 x 5 = 30

2 x 3 x 7 = 42

Select the common factors.

2 x 3 = 6, the GCF

Answer 7

Fractions don't have factors.

Answer 8

The least common factor is always 1.