Supporting your child in Addition and
Subtraction Strategies
Dear Parents,
This handout helps explain different addition and subtraction strategies your child is learning at
school. We teach children a range of different ways to add and subtract numbers. We want
them to look for patterns and use them as much as they can. We want them to have good
number sense – an understanding of how and why different ways to add and subtract work well.
The goal is for them to be able to do it in their head in a way that makes sense to them.
You can add in any order but not subtract in any order
36 + 45 = 45 + 36 but 76 – 32 ≠ 32 – 76
Counting on and counting back
14 + 3 …
start at 14, then count on to 17 ie 15, 16, 17.
12 – 3 …
start at 12 then count back to 9, ie 11, 10, 9.
Using Addition and Subtraction number facts
If 17 + 3 = 20 then 20 – 17 = 3 and 20 – 3 = 17
To bridge to 10
Bridging is a strategy whereby students are asked to make ten first and then add the left over
amount. Find the nearest 10
For example:
8+6=
8 become 10 by taking 2 out of 6.
It makes it easier 10 +4= 14
17 + 5=
17 and 3 become 20 and add 2 more
27+35=
27 and 3 becomes 30 then add 32
Addition facts to 10
(Friends of Ten)
0 + 10, 1 + 9, 2 + 8, 3 + 7, 4 + 6, 5 + 5
Doubles
1 + 1, 2 + 2, 3 + 3, 4 + 4
Splitting numbers into 10s and ones
62 = 6 tens and 2 ones
Counting up in 10s
eg 5, 15, 25, 35, 45 or 2, 12, 22, 32
etc for 58 + 30 start at 58, then think 68, 78, 88
Counting down in 10s
eg 97, 87, 77, 67, 57 for 85 – 40
start at 85, then think 75, 65, 55, 45
Split Strategy
Numbers are split into tens and ones. For example, 46 becomes four tens (40) and six ones (6),
and 33 is three tens (30) and three ones (3).
Addition
Splitting the tens and only one group of ones:
33 + 35 =
33 + 30 = 63 + 5 = 68
Therefore 33 + 35 = 68
Splitting the tens from the ones:
46 + 33
= (40 + 6) + (30 + 3)
= 40 + 30 + 6 + 3
= 70 + 9
= 79
This makes it easier to add the tens and the ones (40 + 30 + 6 + 3)
Subtraction
63 – 35=
63 – 30 = 33 – 5 =28
Or
67 - 43=
67 – 7 = 60 and 43 – 3 =40
60 - 40 = 20 and 7 – 3 =4
20 + 4=24
Therefore 63 – 35= 24
Jump Strategy
Addition
Start from the largest number and jump forward from it to get
the final answer.
46 + 33 = 79
It could be done ...
46 + 10 + 10 + 10 + 1 + 1 + 1
or it could be done ...
46 + 10 + 10 + 10 + 3
Jump Strategy continued
Subtraction
87 – 34 = 53
could be done... 87 – 10 – 10 – 10 – 1 – 1 – 1 – 1
or it could be done ... 87 – 30 – 4
Compensation strategy
Addition
The compensation strategy for addition is useful when one of the numbers ends in 8 or 9. One
number is rounded up to the next 10, the addition is carried out and then the answer is adjusted
to compensate for the original change.
59 + 23= Round off 59 to 60 the subtract 1 at the end
60 + 23 =83 – 1 =82
Subtraction
59 – 23 = Round off 59 to 60 then subtract 1 at the end
60 – 23 = 37 – 1 =36