Mental Strategies Addition (+) and subtraction (-)

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 by the end of Year 2.

 

To develop number sense, students learn:

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.
To bridge to 10	Find the nearest 10 eg 17 + 5; 17 and 3 is 20 and add 2 more
Addition facts to 10	0 + 10, 1 + 9, 2 + 8, 3 + 7, 4 + 6, 5 + 5
Doubles	1 + 1, 2 + 2, 3 + 3, 4 + 4
Doubles + 1	1 + 2, 2 + 3, 3 + 4, 4 + 5
Splitting numbers into 10s and ones	62 = 6 tens and 2 ones
Counting 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
You can add in any order but not subtract in any order	36 + 45 = 45 + 36 but 76 – 32 ≠ 32 – 76

 

This could be helpful in understanding the terminology used in class when encouraging your child to practice and understand mental strategies. Remember they have until the end of Year 2 to perform simple addition and subtraction calculations using a range of strategies.