I taught it this way for 20 years. It works.
this post was submitted on 23 May 2026
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The niner table is one of the easier ones. Add first and second digit, and you'll get a nine.
What kids are really struggling with regularly are the seveners.
The nine timestable was one of the easier ones for me to learn as a child because I recognized the pattern in the numbers:
- 09
- 18
- 27
- 36
- 45
- 54
- 63
- 72
- 81
- 90
First row of digits go 0123456789 while the second row goes 9876543210. Idk, I thought it was cool that they did that.
The timestables that I had the most difficulty with were 7 and 8.
The trick I was taught is that the sum of all two digit multiples of nine add up to nine. Then you just take the number you want to multiply times none and subtract 1.
For example if you want to multiply times 8, the tens place is 7 and the ones place must add up to 9, so 2. 7+2=9, so 9x8=72.
Isn't it easier to just do 80 - 8
not for me. I do the "adds up to 9" trick to this day.
The method I'm talking about only adds/subtracts single digit numbers, which is easier for kids.
Oh. Haha, this was how I was actually taught to do the 9s. I think it was meant as just a "you can also do the lower ones this way" and wasn't suppose to be "the only way you'll remember, Rebekah" but it was the second one!
"Cheats" like this is why critical thinking is fucked...
Kids are supposed to learn:
Times 10 adds a zero, minus one from that is times 9
And different steps for different rows/columns.
We shouldn't "memorize" the times tables, because that's just memorization. These cheats learn a process, but it dead ends at this, it can't be used as a foundation to build on the real skill it should be developing: doing multiple math steps in your head.
If done right it "times tables" are the most important building block in being good at math. But for decades teachers just care if the right answer is spit out.
I agree the the number-theoretic shortcuts for multiplication (and division!) based on the factors of 9, 10, and 11 should be taught.
I disagree that single-digit sums and products shouldn't be memorized. Neither students nor practitioners derive formulae from first principles each and every time, and breaking down a single-digit sum or product into "simpler" ones is a very similar ask.
Neither students nor practitioners derive formulae from first principles each and every time,
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If they have it memorized, it's from years of usage, they didn't need to practice moroizing the things theyd use every day. Because it would happen anyways.
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Math class isn't applied Math, it's just Math. Giving credit for memorizing someone else's equation is a way to push people thru who can't do the math.
And even in a hypothetical world where someone needs to apply an existing mathematical formula that they don't use constantly, they're not gonna just risk it to save 2 seconds checking.
I understand why you have the opinion you have, but that doesn't mean our education system was blinded in the pursuit of metrics generations ago, hell, it's ancedotal evidence it did...
I use my memorized times tables in my head a lot more often than many other math skills. But maybe I'm just weird, I'm certainly no math whiz. Yet.
Edit: I realize this may just be because I don't have many other math skills, to your point.
We shouldn't "memorize" the times tables,
While I agree with your sentiment, times table memorization is necessary to build a skill that will be needed later in math. It's good to teach the basis of the times table but if you don't have it memorized, every later math problem will be slower to solve because you will be focusing on the principles of how a times table works instead of the new concept like how to multiply long number with carry.
This is related to my pet peeve, that despite it being 40 years ago is still burned into my memory. I had many Physics professors who would talk about not needing to memorize formulas for exams because they could be derived from first principles. Those same professors were always the ones who would give exams that if you didn't have formulas memorized, there wouldn't be time to finish.