195, 390, 585 and so on.
Multiples of 15 include 15, 30 and 45. For them to be common, they need to be compared to another set of multiples.
There aren't any in that range.
Multiples of 13 include 13, 26, 39 and so on. For them to be common, they need to be compared to another set of multiples.
They are the six multiples of 15.
The multiples of 15 are 15, 30, 45, 60, 75 and so on. For them to be common, they need to be compared to another set of multiples.
Two common multiples of 21 and 15 are 105 and 315.
There are infinite common multiples for a set of numbers. So it is not possible to write down all the common multiples. Some common multiples of 15, 30 and 45 are 90, 180, 270, 360,... There is another way to find common multiples: Write the multiples of LCM(15, 30, 45). Actually the common multiples of a set of numbers are the multiples of their LCM. LCM of 15, 30 and 45 is 90. And the multiples of 90 are 90, 180, 270, 360, 450, 540,... which are the common multiples of 15, 30 and 45.
The least common multiples of 5, 11, and 13 is 715.
3:3,6,9,12,15,18,21,24,27,30,33,36,39,42,45,48,51,54,57,60,63,66,69,72,75,78,81,84,87,90,93,96,99 15:15,30,45,60,75,90,105
Multiples of 15 include 15, 30 and 45. For them to be common, they need to be compared to another set of multiples.
The common multiples of 6 and 13 are the infinite set of multiples of their LCM, which is 78. So the common multiples of 6 and 13 are 78, 156, 234, 312, 390, and so on.
78 and any of its multiples