Dr. Avraham ben Ezra
https://www.hayadan.org.il/klallnokllal.html
The science teacher entered the classroom without being able to hide his smile that peeked out from under the surface, a smile familiar to the students whenever there was a surprise in his mouth - and indeed that is what happened in that lesson:
"Look, my beloved students" - he began and said - "have you noticed that 12×12=144 and the inverse of the multiplied numbers also give the inverse of the result? Here you see: 21×21=441, moreover, even if we check further, this rule is preserved - because: 13×13=169, and of course the reverses of the numbers again give the written result from the end to the beginning - 31×31=961".
"It's clear," Shira said, "after all, we reversed the multipliers, so the multiplication was also reversed."
Then the science teacher wrote on the board the following table illustrating the aforementioned rule regarding the first four two-digit numbers as follows:
(see table at the top of this page)
And not a single student thought of accomplishing the accounting rule he had just learned, but... that the science teacher accomplished and said as his smile rose like a rising spring:
"Well, students, this rule is not a rule at all, because... all this happens but by chance, and later - it is not like that, try and argue.
And now, we are all ready to start studying the next topic, and it is - of course - induction..."
Science - books
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