What is the GCF of 15 and 6?

Answer 1

3.

15/3=5
6/3=2

Answer 2

the GCF of 15 and 6 is 3.

list the prime factors of both numbers:

15 = 1 x 3 x 5
6 = 1 x 2 x 3

both have 1 and 3 in common. the product of their common prime factors is 3.

Answer 3

3

Answer 4

3

Answer 5

For small numbers such as this, decompose into prime factors:
15 = 3 * 5
6 = 2 * 3

Find numbers that are common in the list for both numbers.
In our case, it's just 3. Answer is hence 3.

If you have something like gcf of 18 and 27,
18 = 2 * 3 * 3
27 = 3 * 3 * 3
So each has two threes. so gcf is 3*3 = 9

For bigger numbers which dontlend themselves to easily being decomposed into primes - say a 20 digit number made up of 5 digit primes, look up Euclid's technique for getting primes.

Answer 6

3 is the GCF because each number (15 and 6) can be divided by 3.

Answer 7

To find GCF, you have to know what the prime factors of each number are:
15 = 3 x 5
6 = 2 x 3
Now you would list all the "common" ones (the ones they both have).
That would be only "3". So it's the GCF.

If they had had more prime parts in common, you would've taken all the common ones and multiplied them up and that would've been the "greatest" common factor.

Answer 8

The Answer:
factors of 15:1,3,5,15
Factors of 6: 1,2,3,6

The largest factor among the two list is 3, thus, the GCF. QED

Answer 9

The greatest common factor of 15 & 6 is 3.

15/3=5
6/3=2

Answer 10

6=2x3
15=3x5

3 is the GCF because both can be divided by 3