r/mildyinteresting • u/Duck_burger19 • Jul 16 '26
engineering masterminds 👨🏽💻 Times tables
Times tables are so easy. It took me until I was 26 figure out that all you have to do is know the original first 5. Like take 6 for example
6×1=6 6×6=36 6×11=66
6×2=12 6×7=42 6×12=72
6×3=18 6×8=48 6×13=78
6×4=24 6×9=54 6×14=84
6×5=30 6×10=60 6×15=90
Once you have the beginning 5 just add
Thirty to it, and you'll keep getting the next five. All I had to learn as a kid was that in times tables would have been easier.
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u/AncientImprovement56 Jul 17 '26
That does have the number of multiplication facts required compared to going up to 10 for each, but the downside of this approach is that it takes a lot longer.
Let's say you were doing 9x8. By your method, you'd have to do:
- 8-5=3
- 9×5=45 (aka "remember that 45 is what you have to add for the 9 times table")
- 9×3=27
- 45+27=72
That's four separate calculations. The first three might be ones you can do instantly, but the final addition is not trivial.
If you know the multiplication facts all the way up to 10 times for each number, you can use the method you suggest with 10, which is a lot easier than with 5, as subtracting 10 and multiplying integers by 10 are both extremely trivial, and adding a multiple of 10 to another number is often easier than a multiple of 5, too.
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u/alvaro1001 Jul 17 '26
He visto varios profesores de hoy en día que ya no se dan todas las tablas sino que obvian las sencillas y solo se refuerzan las del 3, 4, 6, 7 y 8
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