Stage 2 · Unit 42 / 44 · Numbers & Operations
Use 10 to subtract
When the ones are not enough, as in 14 − 9, use the 10. This is the idea behind borrowing.
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Take away the ones first
Take 4 from 14 first to reach 10.
Split the number you take away
For 14 − 9, split 9 into 4 and 5: 14 − 4 − 5.
· Not the suggested orderFinish from 10
· Not the suggested orderSplit the first number
For 13 − 4, split 13 into 10 and 3: 10 − 4 + 3.
· Not the suggested orderTake from the 10 first
· Not the suggested orderAdd what is left
· Not the suggested orderAbout Use 10 to subtract practice
“Use 10 to subtract” is unit 42 of Stage 2, for ages 7–8, in numbers & operations. When the ones are not enough, as in 14 − 9, use the 10. This is the idea behind borrowing.
Its steps are: Take away the ones first, Split the number you take away, Finish from 10, Split the first number, Take from the 10 first, Add what is left. Each step has 10 problems and is free with no sign-up. 90% or better earns three stars.