Well, here's another way you can multiply a fraction with a whole number : convert the whole number into a fraction itself. It would simply be that whole number over 1. (
)
So that would make it :

×

. You multiply 600 and 1, you get 600. You multiply 3 and 1, you get 3. This has you end up with :

After that, you would have to divide 600 by 3.
600 ÷ 3 =
200