What are the method in using greatest common factor?

Answer 1

First: how many numbers there are. break it down like..............

45 15

/\ /\

9 5 5 3

/\ 5 stays since it's prime, same as 3

3 3

Then: do this......

45: 3x3x5

15: 5x3

circle 3's like, the bottom 3 to 1 top 3, and 1 bottom 5 and 1 top 5 until it's............

3x5, so the GCF of 45 and 15 is 15

Answer 2

A simple, but somewhat slow method, is Euclid's method.

1. Write down the numbers.
2. Find the smallest number.
3. Subtract it from each of the larger numbers.
4. If all the numbers are now the same then that is the GCF, otherwise go back to step 2.

For example, to find GCF 3, 12, 18

6 15 18: min = 6

6 9 12: min = 6

6 3 6: min = 3

3 3 3. All are equal so GCF = 3.

Answer 3

Example: 30 and 42
Step 1: Factor them.
2 x 3 x 5 = 30
2 x 3 x 7 = 42
Step 2: Select the common factors.
2 x 3 = 6, the GCF

Answer 4

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

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

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 8

Finding the prime factorization.