Many other numbers share some multiples with 15.
However, only two numbers share all of 15's multiples: 3 and 5.
15, 30, 45, 60, 75 & 90
15 and 1
3 and 5
1 x 810, 2 x 405, 3 x 270, 5 x 162, 6 x 135, 9 x 90, 10 x 81, 15 x 54, 18 x 45, 27 x 30 = 810
Factors are the numbers you multiple together to get another number. 15: 1, 3, 5, 15
Each of these factor pairs (multiply the numbers in parentheses) equal 15: (1, 15) (3, 5)
The general rule is that the product of the LCM and the GCF is equal to the product of the original two numbers. That would make the answer 20. Lets overlook the fact that two numbers with a GCF of 15 and an LCM of 20 don't exist.
These: 1, 2, 3, 5, 6, 10, 11, 15, 22, 30, 33, 55, 66, 110, 165, 330 Multiplied as: 1 x 330, 2 x 165, 3 x 110, 5 x 66, 6 x 55, 10 x 33, 11 x 30, 15 x 22
95
15 and -3
-13
15 x 15 = 225
17
8, 5 and 2
They are: 1*3*5 = 15
-5 x 21= -105
15 and 8
They are -3 and -5
-8 and -15
-177