Unit 7 - Addition

• Mathematics
• Primary Education
• Age 9

Unit 7 - Addition / Subtraction

By: Mr Sacha

This Lesson

We will learn:

 - How to add multiple single digit numbers quickly.

 - How to spot pairs of numbers that make addition quicker.

Refresher

Go to this website. Follow the teacher's instructions. 

https://www.mathplayground.com/index_addition_subtraction.html 

Complementary Numbers

Work out the totals in both numbers.

Which one did you find more easily?

.

In your own words, what are complementary numbers?

Complementary Numbers

These are 2 numbers that add up to 10. 

Like 4 and 6, or 3 and 7.  

Finding complementary numbers is easier and faster than adding up numbers one at a time. 

Lets try it! 

Add the results of these dice together!

How did you do it?

.

Another one!

Add the results of these dice together!

How did you do it?

.

Last one!

Add the results of these dice together!

This one is 10

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How did you do it?

.

Remember

The order of addition doesn't matter. 

6+3 + 4+7 is the same as

7+3 + 6+4                               

So you can add the easy complementary numbers first, 

then add on what is left over. 

Work

Put your device away.

Work on the questions in workbook p57