Question

how do find the LCM other than listing the multiples out

Answer 1

Find the prime factors and multiply the union of the two.
Ex:
12 and 16
12: 2*2*3
16: 2*2*2*2
We need 4 twos and 1 three
2*2*2*2*3=48

Answer 2

Notice I only used four 2's even though I had a total of six of them. This is because I used the smallest amount I could and still have all the prime factors of both numbers.
(2*2*2*2)*3=48 - This shows the factors of 16
2*2*(2*2*3)=48 - This shows the factors of 12

Answer 3

multiply all the prime factors togeather