Post #4159616
2025-10-24 12:26 UTC
When you learned to subtract numbers by hand, did you learn it with this "borrowing" method?
I forgot how to subtract say 384 from 2173 and asked some chatbots "how do you subract by hand with pen and paper". They all explain it with this super strange borrowing method. Here in Switzerland I just learned to add a 1 if you cross zero...
Replies (2)
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@wipfli@mastodon.social 2025-10-24 12:33
I learned it like this...
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@gnaddrig@mastodon.social 2025-10-24 13:58
@wipfli@mastodon.social Same here in Germany in the 1970s. You count upward from the 4 in 384 until you get to 3, and when crossing the 0, you add 1 to the 8 in 384 and write down 9 as the last digit of your result. Repeat for the 8+1 in 384 until you get to 7, add 1 to the 3 in 384 and write down 8 as the second-before-last digit of your result. Repeat for the 3+1 of 384, add 1 to the 0 that is the fourth-from last digit of 384, write down 7 as the third-before-last digit. /...