Formal column subtraction
As well as requiring confidence in subtracting single digits, the formal column method for subtraction requires a knowledge of place value and a sound understanding that subtraction is not commutative . There are different column methods which can be used, but we focus here on the method involving exchanging, also referred to as regrouping or trading. Whilst often called 'borrowing', this term implies that something will be given back, which is not the case with the method, and this can cause confusion. As my daughter suggested, we should call it 'stealing' rather than 'borrowing'!