LCM

Finding the Lowest Common Multiple (LCM)

A common multiple is a number that is a shared multiple of two or more numbers. For example, 24 is a common multiple of 8 and 12, as 24 is in the 8 times tables (Equation: 8 times 3 = 24) and 24 is in the 12 times tables (Equation: 12 times 2 = 24).

The lowest common multiple (LCM) is found by listing the multiples of each number and circling any common multiples. The lowest one is the lowest common multiple.

In some questions the highest common factor (HCF) or lowest common multiple (LCM) of two very large numbers may need to be found.

It would take a long time to write out all the factors and multiples of 24 and 180 and compare the lists. An error could easily take place.

A much simpler method is to use prime factors.

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