UK Primary (3-6)
topic badge
Complete factor expressions (below 100)
Lesson

We can make any number by using its factor pairs. Every number will have at least one factor pair, $1$1 and itself. 

When we're completing factor expressions we need to think of a second number we can use to complete an expression. We can do this by counting or maybe dividing. Let's look at an example...

Complete the factor expression below

$\editable{}$$\times$×$7=21$7=21
 

Here we need to complete the factor expression by finding what goes in the $\editable{}$.

So far we know two numbers $7$7 and $21$21. We can use these two numbers to work out the missing number. 
We can either find the result of $21\div7$21÷​7 or we can count by $7$7's.

If we count by $7$7's we get...

$7$7, $14$14, $21$21

On a number line it would look like this...



We can now see that we'll have to count by $7$7 three times before we get to $21$21, so $3$3 groups of $7$7 make $21$21

So, the number $3$3 completes the factor expression. 
$3\times7=21$3×7=21

Remember!

We can use the multiplication tables to help us work out factors of a number.

 

Use the sliders below to find that factor pair.  

Examples

Question 1

Fill in the box with the missing number.

  1. $6\times\editable{}=60$6×=60

Question 2

Fill in the box with the missing number.

  1. $11\times\editable{}=22$11×=22

Question 3

Fill in the gaps to find all factor pairs of $66$66.

  1. $1,\editable{}$1,

    $2,\editable{}$2,

    $3,\editable{}$3,

    $11,\editable{}$11,

What is Mathspace

About Mathspace