LCM

Suppose we want the LCM  for 60 and 42

"Prime factor" each

60  = 2^2 x 3 x 5

42 = 2 x 3 x 7

Put the like prime factors over each other like this:

2^2      3       5

2         3               7

Select the different factors with the highest powers....if the same factor has the same power, select either one.....so we have....

2^2, 3, 5, 7       multiply these together

4 x 3 x 5 x 7 =  420   and that's the LCM