LCM( 1, 42, 7 ) = 42
Write down multiples of each number until you find the first common multiple:
The multipliers of 1 are: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, . . .
The multipliers of 42 are: 42, 84, . . .
The multipliers of 7 are: 7, 14, 21, 28, 35, 42, 49, . . .
We can see that:
LCM( 1, 42, 7 ) = 42
This solution can be visualized using a Venn diagram.
The LCM is equal to the product of all the numbers on the diagram.