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Back through ten
Back-through-ten strategies involve using decades as landmarks to solve harder calculations. For example, 52 – 8 = ? can be solved by calculating 52 – 2 = 50 then 50 – 6 = 44.
The back-through-ten strategy tends to be more difficult than the up-through-ten strategy because it involves breaking down numbers, as opposed to building them up. However, the same key knowledge of facts to 10 and place value is required. You can watch the Back through Ten video.
You can download the Back through Ten video transcript.
Back-through-ten strategies can be practised using the learning object L97 The takeaway bar: make your own easy subtractions
These ideas are further explored in Place Value and Number Facts: Addition and Subtraction.
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