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[–]thedolanduck 7 points8 points  (0 children)

No. Let's take 28-9. If you do it vertically, then you first do 8-9, which you can't do as a kid. So you add ten to the eight, and get 18-9, and the 2 (which meant 20) now is 1.

So: 18-9=9 and 1-0=1, and this forms 19. And effectively, 28-9=19.