Pupils need to have a strategy for confidently and fluently carrying out calculations such as:
- 7 + 5 = 12
- 15 – 9 = 6
For both addition and subtraction across 10, tens frames and partitioning diagrams can be used to support pupils as they learn about these strategies. First, pupils should learn to add three one-digit numbers by making 10, for example, 7 + 3 + 2 = 10 + 2. They can then relate this to addition of two numbers across 10, by partitioning one of the addends, for example 7 + 5 = 7 + 3 + 2.
Pupils can subtract across 10 by using:
- the ‘subtracting through 10’ strategy (partitioning the subtrahend) – part of the subtrahend is subtracted to reach 10, then the rest of the subtrahend is subtracted from 10
- the ‘subtracting from 10’ strategy (partitioning the minuend) – the subtrahend is subtracted from 10, then the difference between the minuend and 10 is added.
You can find out more about fluency and recording for these calculations here in the calculation and fluency section: 2AS–1