First three common multiples of 15 and 20 would be: 60,120,180
15 & 20 have an infinite number of Common Multiples; the first three are 60, 120 and 180.
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.
LCD= 60
60,120,180,240,300.... infinity
The multiples of 20 are 20, 40, 60, 80, 100, 120... The multiples of 30 are 30, 60, 90, 120, 150... The multiples of 15 are 15, 30, 45, 60, 75, 90, 105, 120, 135... The common multiples of 20, 30, and 15 are 60, 120, 180, 240...
60 and 8,220
The LCM is 60
60
The Least Common Multiple (LCM) for 10 15 20 is 60.
Multiples of 5 include 5, 10, 15 and 20. For them to be common, they need to be compared to another set of multiples.
They are both multiples of 5