Find the greatest common factor of 15x2y3 and -18x3yz.

For this case we have that by definition, the GFC (greatest common factor) of two numbers is given by the greater number that is a factor of both numbers. Then, let:

We decompose into factors:

15: 1,3,5,15

18: 1,2,3,6,9,18

The GFC is 3.

So, we have that the GFC of the expressions is:

add all the numbers and check the ones place.

the answer is 486. as the ones place is more than 4, the estimation will be the next 10 ie, 490