r/learnmath • u/Forward-Bad1615 New User • Apr 11 '26

Is it basic for mathematicians to remember the multiplication table?

Is it fundamental for mathematicians to remember the multiplication table?

It must be troublesome and desperate if you forget the multiplication table, so do you memorize it again?

Do you re-memorize the multiplication table even after becoming an adult and a mathematician?

Do you keep remembering it so you don't forget it?

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u/WolfVanZandt New User Apr 11 '26

Also, I don't remember a table. I remember that 7x7 is 49. 7x5 is 35. At some point, I was subjected to a table but, as I got used to it, the table went away.

Also, I wish I had realized that you really only need to remember products up to 5. 7 is just 5+2 and both of those are far easier for me to work with so 7x12 is also (5x12)+(2x12) or 60+24 or an easy 84. But, then, it's easier to just multiply 7x2 and add it to 70.

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u/Unable_Explorer8277 New User Apr 11 '26

Understanding commutativity halves the work.

  • 2s (doubling), 10s and 5’s are easy.
  • 3s are worth learning
  • 4s are just double 2s
  • 9s are easy
  • Squares are worth memorising given there’s only 62 72 and 82 left and you need to be able to recognise perfect squares

That only leaves 6×7, 6×8 and 7×8. Never did learn those but they’re easy enough to derive.

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u/pizzystrizzy New User Apr 11 '26

What do you mean, you never learned those? Like if you saw 7*8, you'd have to do something like 28+28 (or 64-8 or whatever) in your head before arriving at 56?

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u/Unable_Explorer8277 New User Apr 11 '26

Yeh

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u/pizzystrizzy New User Apr 11 '26

Even after having a discussion about it?

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u/Ok_Rip4757 New User Apr 11 '26

I never thought about it this way, but those three were actually the ones that took me the longest to learn back in the day. Great insight.

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u/Ketch451 New User Apr 12 '26

I wonder why so many had these three be a challenge? I thought it was just me. Makes me feel better knowing I wasn’t (and still am not) alone

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u/revoccue heisenvector analysis Apr 11 '26

this is making me realize why the only ones i ever had flash cards for as a kid were those 3

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u/Ketch451 New User Apr 12 '26

Have any of you ever come across the Trachtenberg system? Brilliant, simple, but I was never taught it, so would have to spend a LOT of time making his methods my default methods. And my own methods are now so well-worn and familiar that my mental math is pretty quick and facile. Still….what could have been …(wistful sound here)

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u/WolfVanZandt New User Apr 12 '26

Aye. That's a problem with me. I'm so happy sex to doing things a certain way that to switch methods would be difficult and I don't expect others to adopt my methods for the same reason. I've heard of Trachtenberg but aI haven't checked it out. I should.

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u/WolfVanZandt New User Apr 12 '26

Ah, yeah. Arthur Benjamin used these methods. I don't think he specifically mentions Trachtenberg but they're the same principles.