Using number lines in Addition and

Subtraction

By Amani El-Alawneh

Adding numbers using the number line.

4725

So how do we do this using the number line?

We use the strategy called:

Counting Up

You need to think about:

What number shall I start with on my number line?

What number do we want to count up by?

Are there any number bonds that can help me?

25 + 47 =Use the counting up method!!

So we start at the biggest number…47

And count up 25 placesWhat number do we end on???

So….

25 + 47 = 72

47

+20

67

+3

70 72

+2

Use the Counting Up Strategy

Remember -You need to think about:

What number shall I start with on my number line?

What number do we want to count up by?

Are there any number bonds that can help me?

+ 34 = 57?

34

44 54 57

+10 +10+3

So what is 34 57

10 + 10 + 3 = 23

So…..

+ 34 = 5723

+ 34 = 57

Can I use the counting up strategy for Subtraction too?

Have a look at this question!

43 – 27 = What number shall I start from on my number line?

27

What number shall count on by?Can any number bond make counting on easier for me?

37

+10+3 +3

40 43

10 + 3 + 3 = 16

16

What number do I want to get to?

YES

32 - = 18

What number shall I start from on my number line?

What number do I want to get to?

What number shall count on by?

Can any number bond make counting on easier for me?

18

20 30 32

+2

+10

+2

2 + 10 + 2 = 14

So….

32 - = 1814

Have a go at these questions now using number lines and the counting on strategy:

1. 45 – 25 = 2. 54 – 26 =3. – 19 =364. 28 – = 145. 43 – 37 =

6. 55 + 18 =

7. 29 + 40 =

8. 33 + = 51

9. + 14 = 35

10. 22 + 15 =

Extra for Experts:

1. 154 – 147

2. 172 – 133

3. 198 – 188

4. 134 – 119

5. 176 - 134

6. 123 + 19

7. 199 + 98

8. 147 + 76

9. 201 + 97

10. 185 + 89

Work out the following calculations mentally:

• 43 – 37• 102 – 98• 154 – 147• 3005 – 2997

+4

40

+3

How can we show this using the number line:

37

43

43 – 37

+33 + 3 = 6

So,

43 – 37 = 6

154 – 147

147

150

154

+3 3 + 4 = 7

So,

154 – 147 = 7

Have a look at these Calculations

• 144 – 138

• 89 – 34

• 134 – 123

• 125 - 76

What is it about the numbers that made you decide to use mental

method or a number line?

Do you always need to use a number line when the numbers are a

long way apart??

- 285 = 39

285 300

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