What is the next number in the series 60 30 20 15 12?

10

explanation:

from 60 to 30 you multiply by 1/2

from 30 to 20 you multiply by 2/3

from 20 to 15 you multiply by 3/4

from 15 to 12 you multiply by 4/5

from 12 to 10 you multiply by 5/6