what is the least common multiple of 63 and 200?
You have to break each down into their prime factors. The LCM will be the smallest multiple that has all prime factors..
63 = (3)(3)(7) .... need two 3's and one 7
200 = (2)(2)(2)(5)(5) need three 2's and two 5's
LCM = (2)(2)(2)(3)(3)(5)(5)(7)
Note in most cases you don't end up with all numbers if there are duplicates (like if there was a (2) in the first number and a (2) in the second number you would only need to put it once.