Write down multiples of each number until you find the first common multiple:

The multipliers of 36 are: 36, 72, 108, 144, 180, 216, 252, 288, 324, 360, 396, 432, 468, . . .

The multipliers of 54 are: 54, 108, 162, 216, 270, 324, 378, 432, 486, . . .

The multipliers of 108 are: 108, 216, 324, 432, 540, . . .

The multipliers of 144 are: 144, 288, 432, 576, . . .

We can see that:

LCM( 36, 54, 108, 144 ) = 432