Do you know the definitions of the least common multiple and the greatest common divisor? It's best to look at Baidu Encyclopedia and review it.

36=2*2*3*3

24=2*2*2*3

54=2*3*3*3

Then the greatest common divisor is 2*3=6.

The least common multiple is 2 * 2 * 2 * 3 * 3 = 2 16.