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
+
+