What are the common multiples of 9 15 and 20?

The common multiples of 9, 15, and 20 are an infinite set of multiples of their least common multiple, which is 180. so the common multiples of 9, 15, and 20 are 180, 360, 540, 720, 900, 1080, 1260, 1440, 1620, 1800, and so on.