Find Multiples and Lowest Common Multiples

In this activity, we will be learning about lowest common multiples. But first, let's have a look at what we mean by the word multiple.  

A multiple is a number that is divisible by another number without leaving a remainder. 

For example, 15 is a multiple of 5. You can also think of it as 'Is 15 in the 5 times table?'

Multiples of 5 are 5, 10, 15, 20, 25..and so on.

Multiples of 3 are 3, 6, 9, 12, 18.. and so on. 

We can test whether or not a number is a multiple of another number by using the chart below. This works well for big numbers that will take a bit longer to divide. 

For example:

The number 975 

- Is not a multiple of 2 since it does not end in 0, 2, 4, 6 or 8 

-  Is a multiple of 3 because if we add the digits 9 +7 + 5 = 21, we get a multiple of 3

- Is not a multiple of 4 because the last two digits, 75, do not make a multiple of 4 

- Is a multiple of 5 because it ends in a 5 

So to conclude, 975 is a multiple of 3 and a multiple of 5.   

The lowest common multiple of a set of numbers is found by identifying the multiple which they have in common with the lowest value.

For example, to find the lowest common multiple of 2 and 5. 

Step 1: Write down the multiples of 2 and 5.  

Step 2: Identify the smallest multiple which they have in common.

The lowest common multiple of 2 and 5 is 10.

Do you feel ready to have a go at some questions now?