Question

What is a common multiple of 6,12and 10

Answer 1

There are an infinite number of them.
The smallest one is  60, and every multiple
of 60 is another one.

Answer 2

$LCM(6;\ 12;\ 10)\\\\6=\fbox2\cdot\fbox3\\12=\fbox2\cdot2\cdot\fbox3\\10=\fbox2\cdot5\\\\therefore\\\\LCM(6;\ 12;\ 10)=\fbox2\cdot\fbox3\cdot2\cdot5=\boxed{\boxed{60}}$