When I was very young, my father (born in 1920) quizzed me once on my mental addition and subtraction talents.
He was satisfied with my addition.
But my subtraction enraged him.
He asked me (for example) “What is 8 minus 10?”
I hadn’t learned negative numbers yet, so I said “You can’t do that!”
After a little back-and-forth I discovered that what he called 8 minus 10 was equivalent to what I called 10 minus 8. I had to mentally reverse each problem to get the correct solution. Meanwhile, he was engaged at our terrible school system and the nonsense they were teaching these days.
What was going on there? Was subtraction basically different back in the day?
Would the above problem be written 10-8 but read aloud “8 minus 10”?
Or was it also written 8-10?
I’ve never heard of this again, even from old timers (tho I don’t typically discuss arithmetic with people).
Could this be related to his coming from a Mediterranean country, or New York schools? I don’t think he ended up graduated from high school, but he was quite brilliant so he must have learned this somewhere. Is it a regionalism?
Certainly it’s possible that he forgot, tho I think it unlikely.
I suspect it is something Yoda-ish, where, when read aloud, the numbers are reversed. I wonder if it’s old-fashioned, or regional, or an ESL affect. If it’s old-fashioned, when did it come out of style?
Arabic and Hebrew are read from right to left. So somebody used to working in those languages and translating what he’s reading into English might reverse the expression.
10 - 8 would be pronounced in modern (post-1960s) schooling as “ten minus eight”. With the obvious answer being “two”.
10 - 8 would be pronounced in earlier (pre-1960s) schooling as “eight from ten”. With the obvious answer being “two”.
I suspect the OPs Dad was using his old way of thinking and reading but had updated his terminology, thinking that “minus” was merely a new fancy technical synonym for the older word “from”. Without him realizing that change also required re-ordering how the equation is read.
I think “eight from ten” mixed up with “minus” makes the most sense. I vaguely remember hearing the “eight from ten” type recitation in old movies, books, and possibly from elders.
He was definitely not asking about negative numbers. I was in too small a grade for that, and the answers that he deemed correct were all positive numbers.
Thank you for giving me a plausible answer to a forty year old mystery.
To this very day, aren’t IRS forms and worksheets full of instructions like “Subtract line 17 from line 8”? I always have to do a doublethink to parse instructions like that.
More exactly: To do 8-10 you would do: 8 ENTER 10 -
To do 10-8 you would do: 10 ENTER 8 -
(Some RPN calculators have the ENTER key marked with a comma.)
I learned arithmetic in the early 50s, and we always used the “ten minus eight” configuration. Sometimes a “word” problem was phrased differently, but that was an exception.