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Subtraction Method "Borrow" vs. "Shift" Most can remember subtraction using the classic "borrowing" method, such as,   63 - 28 = (50 + 13) - (20 + 8) = (50 - 20) + (13 - 8)* = 35. Here we "borrowed" from the 60, adding 10 to the 3 for 13, and leaving 50 behind to subtract the 20 from. This all looks more familiar if one writes it out in the traditonal way, vertically, crossing out the 6, writing the 1 by the 3, etc. You know, "borrowing."       13   5  63 -    28      35 This is a way to do this, but not the only one. We also can change the problem a bit, and into one that gives the same answer. We do this by "shifting" the numbers an equal amount, in this case by adding 2 to both. Here it is. 63 - 28 = (63 + 2) - (28 + 2) = 65 - 30 = 35. Or vertically,  ... read more

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