We can take prime numbers so they don't have a common factor other than 1.
3, and 5.
So we have to list the multiples to find the LCM
3: 3, 6, 9, 12, 15, 18
5: 5, 10, 15, 20, 25
15 is the LCM of 3 and 5
So, you can notice that if two numbers, lets call them a and b, have no common factor, then [tex]a \times b[/tex] is the LCM.
Hope that helped :)
