For the integers from 1 to 1000, how many multiples of 9 are also multiples of 6?

multiples of 9:

9 18 27 36 45 54 63 72 81 90 ..
multiples of 6
6 12 18 24 30 36 42 48 54 60 66 72 ..

the ones found in each are:
18 36 54 72 ..
that is multiples of 3*3*2 or 18

number of multiples of 18 in 1000:
1000/8 = 55.55..

There 55 of them