# Using number lines in Addition and Subtraction By Amani El-Alawneh.

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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 places What number do we end on??? So…. 25 + 47 = 72 47 +20 67 +3 7072 +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 ?

3444 5457 +10 +3 So what is 3457 10 + 10 + 3 = 23 So….. + 34 = 57 23 + 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 4043 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? 1820 3032 +2 +10 +2 2 + 10 + 2 = 14 So…. 32 - = 18 14

Have a go at these questions now using number lines and the counting on strategy: 1.45 – 25 = 2.54 – 26 = 3. – 19 =36 4.28 – = 14 5.43 – 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 +3 3 + 3 = 6 So, 43 – 37 = 6 154 – 147 147150 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 + +