Subtraction problem

Consider this subtraction problem

1241
- 587

Most people won't like to do this in their head (or even paper)

This subtraction problem could be simplified by subtracting 600 instead of 587

1241-600 = 641

But, we have subtracted too much, 13 (600-587) too much.
So we add the "missing" 13 to the 641 we have. And we get the answer which is 654.

End of Chapter 0

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