We can't answer this accurately without knowing what the other number is.
All of the multiples of 280 are. There are an infinite number of them.
All multiples of 7 and 28 have.
1,2 and 7
14, 28, 42
The multiples of 28 include 28, 56 and 84. For them to be common, they need to be compared to another set of multiples.
280, 560, 840
14, 28, 42
They are: 14, 28 and 42
84, 168, 252
14, 28, and 42
84, 168, 252
14, 28, 42