How do find the LCM?

Answer 1

The LCM (least common multiple) is the smallest positive whole number exactly divisible by two or more given whole numbers. Example: the LCM of 14 and 35 is 70 because 70/14=5 and 70/35=2, and no number smaller than 70 is exactly divisable by 14 and 35.

The LCM can also found be for more complex numbers by taking the multiple of the highest power of prime factors from both numbers. For example, the LCM of 72 and 90 is 360, which is the multiple of the highest power of prime factors from both numbers (23 x 32 x 5 = 2 x 2 x 2 x 3 x 3 x 5 = 360). (Prime factors: 72 = 23 x 32; 90 = 2 x 32 x 5)

For more than two numbers, LCM can be found by taking the multiple of the highest power of prime factors from all numbers. For example, the LCM of 28, 70, and 98 is 4,900, which is the multiple of the highest power of prime factors from all three numbers (22 x 52 x 72 = 2 x 2 x 5 x 5 x 7 x 7 = 4900). (Factors: 28 = 22 x 7; 98 = 2 x 72; 350 = 2 x 52 x 7)