When a number is a multiple of 6, what are the possible values for the ones digits?

I would do this by first listing the multiples of 6 until I start to see a pattern with the one's digit.

6x0=0

6x1=6

6x2=12

6x3=18

6x4=24

6x5=30

6x6=36

6x7=42

6x8=48

...

The digits in bold are the one's digits so those are the only ones we really care about. If you list just them it looks like: 0,6,2,8,4,0,6,2,8

Notice how the first set of 5 numbers seems as though it repeats in the 6th, 7th, and 8th numbers. This probably means the pattern continues infinitely so the first 5 numbers are all the one's digits that can come from multiples of 6. Thus your answer is: 0,6,2,8, or 4