Use Near Doubles to Add Numbers Mentally

In this activity, we are going to look at solving addition questions mentally.

This means that we need to find the answers using just our brains!

Luckily, there are lots of different strategies we can use to help us.

 

In this activity, we are going to use near doubles as a way of adding mentally.

 

Near Doubles

If we are given an addition question where the numbers are nearly the same, we can use our knowledge of doubling to help.

61 + 60 =

We can double 60 and then add 1

 

Double 60 is 120 

120 + 1 = 121

 

Top Tip: To double 60, we can double 6 then multiply by 10

              Double 6 = 12 x 10 = 120

 

Let's have a look at another example.

 

122 + 121 = 

We can double 120  then add 2 + 1 

 

Double 120 is 240

1 + 2 = 3

240 + 3 = 243

 

Top Tip: To double 120, we can double 12 then multiply by 10

                Double  12 = 24 x 10 = 240

 

Now, why don't you have a go at answering some mental addition questions using this strategy?