Mental addition means adding two or more numbers together in your head (without using pen and paper)

Being able to add numbers together in your head is a good skill to learn and will save time

There are a number of different tips and tricks to help with mental addition

If you know your number bonds to ten then you will know immediately that

8 + 2 =10

If you know your number bonds to twenty then you will know immediately that

15 + 5 = 20

If you know your number bonds to one hundred then you will know immediately that

30 + 70 = 100

You can learn number bonds to any number - 10, 20, 30, 40, 100, 1,000 etc

If you are asked to add together 45 and 36 in your head it is much easier to add together 45 + 30 + 6

45 + 30 = 75 + 6 = 81

Similarly, 226 + 133 is much easier as 226 + 100 + 30 + 3

226 + 100 = 326 + 30 = 356 + 3 = 359

This method is particularly useful if you have to add up a lot of single digit numbers

If you are asked to add together 1, 6, 8, 5, 1, and 9

you can do this as

1 + 6 = 7 + 8 = 15 + 5 = 20 + 1 = 21 + 9 = 30

or

1 + 6 = 7 + 8 = 15

and

9 + 1 = 10 + 5 = 15

so

15 + 15 = 30

The numbers 1, 2, 3 and 4 can be quickly added by using the way the numbers are formed

Number 1 is counted as 1 - it is often written without the hook at the top making it a single stroke

Number 2 is counted as 1, 2 - one for each of the two strokes as shown

Number 3 is counted as 1, 2, 3 - one for each of the three parts as shown

Number 4 is counted as 1, 2, 3, 4 - one for each of the four parts as shown

Using this method the sum 1 + 2 + 3 + 4 would be added by counting all the individual strokes of each number - 1, 2, 3, 4, 5, 6, 7, 8, 9, 10

Harvard Reference for this page:

Heather Y Wheeler. (2015). Mental Addition. Available: http://www.tiffanymacbeth.com/Maths/mental_addition.htm. Last accessed

Place Value Adding Number Bonds Mental Addition Adding by Chunking Column Addition Subtracting Subtracting by Chunking Column Subtraction Mental Subtraction Roman Numerals

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by Heather Y Wheeler

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