I think ur asking this for a question like "find the lowest common multiple" (LCM)

there is no need to use massive formulas unless the number is greater then 1trillion.

just use Prime factorisation.

eg. 4 = 2 power of 2
6 = 3 x 2
1001 = 7 x 11 x 13
etc...

take the number and find all possible prime numbers which go ito it. (see examples above)
then...

eg. find the lowest common multiple of 4, 2, 6
4 = 2 squared 2 = 2 and 6 = 2x3
therfore the number must contain 2 squared and 3.
= 2 squared x 3
= 12

find all prime factors of the numbers. and take the common ones out
eg. 2 squared and 2
only use 2 squared because 2 is within 2 squared

then multiply them together.


(i can go on but it would just be useless)