Question 1088723
the best method is by using Prime Decomposition:

16 = 2^4

18 = (2^1)(3^2)

45 = (3^2)(5^1)

So we need at least a 2^4, a 3^2 and a 5^1

x = (2^4)(3^2)(5^1) = 720

@natolino_