There are 2 methods of doing subtraction, the decomposition method where the top line numbers are 'renamed' to allow subtraction, and the borrow and pay back method, where you 'borrow' and later 'pay back' on the bottom line.
In the school we have found, and the children agree that the borrow and pay back method is easier to get a handle on. It will be familiar to many adults.
See the video for a worked example.
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