Study Guides/Maths/Common Multiples of 12 and 18
Study Guide · Maths

How to Find the Common Multiples of 12 and 18

Finding common multiples is a basic arithmetic skill taught in primary school mathematics. To find the common multiples of two numbers like 12 and 18, we first need to list out their individual multiplication tables.

Question (Click to Flip)

What is the Highest Common Factor (HCF) of 12 and 18?

Answer

The factors of 12 are (1,2,3,4,6,12) and 18 are (1,2,3,6,9,18). The highest number common to both lists is 6. So, the HCF is 6.

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Key Facts

A quick trick: Once you find the LCM (which is 36), every common multiple will simply be a multiple of 36 (36x1=36, 36x2=72, 36x3=108).

Numbers have an infinite number of multiples, but they only have a limited number of factors.

Step 1: List the Multiples of 12

A multiple is the result of multiplying a number by an integer (1, 2, 3, etc.). Multiples of 12: 12, 24, 36, 48, 60, 72, 84, 96, 108, 120, 132, 144...

Step 2: List the Multiples of 18

Multiples of 18: 18, 36, 54, 72, 90, 108, 126, 144, 162...

Step 3: Identify the Common Multiples

Now, we look at both lists and find the numbers that appear in both of them. The common multiples of 12 and 18 are: 36, 72, 108, 144... and so on. (This pattern will continue infinitely).

Step 4: Find the LCM

The Lowest Common Multiple (LCM) is simply the smallest number that appears in both lists. From our list, the LCM of 12 and 18 is 36.

Questions and Answers

What is the Highest Common Factor (HCF) of 12 and 18?+

The factors of 12 are (1,2,3,4,6,12) and 18 are (1,2,3,6,9,18). The highest number common to both lists is 6. So, the HCF is 6.

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