80 CALCULATING •^ ADDING WITH A NUMBER LINE
Adding with a
number line
Doing calculations in your head can be tricky. We can use
a number line to help us with calculations, including addition.
It is most useful for calculations with numbers up to 20.
The answer is 70
We need to add 3 to 4,
so next jump 3 places to
the right. This takes us to 7.
So, 4 + 3 = 7
This calculation starts with
the number 4, so first find
4 on the number line.
First, we draw a line
and mark it with
numbers from 0 to 10.
Let’s use a number line to
find out the answer when
we add 4 and 3.
Making leaps
Some calculations involve
using larger numbers.
We can still use a number
line, we just have to make
bigger jumps to find
the answer.
Let's use a number
line with larger
numbers to find 20 + 50.
Starting with the bigger
number, we just have to
jump 2 lots of 10 along our
number line. The answer is 70.
4 + 3 = 7
4 + 3 =?
0 4321 5 6 7 8 9 10
0 4321 5 6 7 8 9 10
0 4321 5 6 7 8 9 10
0 40302010 50 60 70 80 90 100
Jump 2 lots of 10
1 1 1
So, 20 + 50 = 70
The line doesn't have
to be neat – it's just
to help you count
Start counting at 4
Stop counting
at 7
You can use number lines to
work out both addition and
subtraction calculations.
+ + = 3
10 + 10 = 20
080_081_Adding_with_a_number_line_Adding_with_a_number_grid.indd 80 29/02/2016 18:02