Find Least Common Multiple of 12, 20, 28 and 35 by listing out the factors.

LCM( 12, 20, 28, 35 ) = 420

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

The multipliers of 12 are: 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144, 156, 168, 180, 192, 204, 216, 228, 240, 252, 264, 276, 288, 300, 312, 324, 336, 348, 360, 372, 384, 396, 408, 420, 432, . . .

The multipliers of 20 are: 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 220, 240, 260, 280, 300, 320, 340, 360, 380, 400, 420, 440, . . .

The multipliers of 28 are: 28, 56, 84, 112, 140, 168, 196, 224, 252, 280, 308, 336, 364, 392, 420, 448, . . .

The multipliers of 35 are: 35, 70, 105, 140, 175, 210, 245, 280, 315, 350, 385, 420, 455, . . .

We can see that:

LCM( 12, 20, 28, 35 ) = 420