So for context, I went to first grade in mainland China before immigrating to the United States, in China, they teach kids this weird trick that's basically like reciting a "poem" thing, which I didn't remember what it was called until I recently googled it. Its apparantly called the "九九乘法口诀表" or 9x9 Song / "The Nine-nine song" (Wikipedia article: https://en.wikipedia.org/wiki/Chinese_multiplication_table#The_Nine-nine_song_text_in_Chinese).
So like... in 2nd grade, for which I was in the US, multiplication was very easy for me, well... at least up to 10x10. Like idk how to explain it to someone who's doesn't speak a variant of Chinese, and even the rhythm only works for me in Mandarin somehow, when I try to use Cantonese, which is the language I speak at home in the US, I cannot replicate the rhythm to make thay thing work, this "Poem"/"Song" is only available to me in Mandarin, like when I think about multiplying together any 2 single digit number, I instictively use the "九九乘法口诀表".
Like its goes from 1x1 then next lines are 1x2, 2x2, then next are 1x3, 2x3, 3x3, then its 1x4, 2x4, 3x4, 4x4, etc... you get the idea, mutiples of 1, then 2, then 3. So if I need to multiply something by 7, I can start from the line where multiples of 7 are. Sometimes I can remember the exact phrase of it like for example 3x7, without starting from 1x7, then 2x7, then 3x7.
Like I never thought too hard about it, it kinda just became the "normal" way I do multiplication. But someone asked a question on Lemmy about reading analog clocks and I probably didn't answer their question correctly but that was when I kinda was like: oh wow I forgot that my way of multiplication is probably different from everyone else in the west.
Like if you told me to teach a English-Only speaker on how to do multiplication tables, I... um... I don't know how I would teach that, the "九九乘法口诀表" doesn't have the rhythm in English so I doubt converting the it to English would work.
Like even though I speak English as my primary language now, and I barely have any fluency in Mandarin or even Cantonese which I speak at home (and never learned any vocabulary beyond the basics), the "九九乘法口诀表" multiplication thing is always done in mandarin somehow, like its always been stuck in my brain even after all these years in the US.
TLDR answer to my own question. I do it using "九九乘法口诀表" which takes me 1-2 seconds to recall a specific line, so basically, anything up to 10x10 takes about 2 seconds for my brsin to process, 11x11x to 12x12 takes about 5-10 seconds, anything bigger and I just giveup using my brain and pull out a calculator. I memorized 10x10 since first grade, then 12x12 probably by like 2nd grade or maybe first half of 3rd grade.
How do y'all do it, is it easy or hard?
Edit: Okay so the best way for me to explain "九九乘法口诀表" is that: Think of PEMDAS (order of operations), but its for the entire multiplication up to 9x9.
I want to say we were supposed to learn them in second grade in Canada, but I personally never did. My memory isn't good enough, so to this day, I just work it out in my head. For small numbers like 1-12, its easy enough to break it down to smaller parts and solve quickly anyway.
Same here. Nobody ever noticed, so why even bother with memorizing if I can calculate it fast enough.
Because it functions as a base for doing slightly more complicated math in your head.
If you don't have 7x7 memorized, it's a lot harder to do 77x70.
But we have calculators... everywhere
Which is totally fine if you do calculations like that every once in a while. If your job or hobby requires frequent multiplication by not-nice numbers, it can be extremely convenient to be able to do this kind of math mentally. Even if it's just a couple seconds, it can be really annoying having to "switch gears" to grabbing a calculator
It's also really nice to just be able to do grocery store math without pulling out your phone. Are the 12 packs or the 24 case cheaper?
And that's probably one of the few remaining uses of mental arithmetic I have nowadays. I also got to practice rounding up numbers for estimating whether or not I've got enough money for groceries. It's easier to keep up with a running total in my head if they're nice (rounded-up) numbers instead of being surprised at the total cost at the end.
I would have no fucking chance in American places that add tax at the till instead of on the sticker.
Im good at keeping a running total in my head and even figuring out if the 2-for-1 on premium brands works out cheaper than 1 super-budget and shit like that.
If im trying to add 17.5% on top of everything I think id just die.
Yeah, even if'd think of it as a flat 20% tax on top (as an estimate), it'd still be a bit too much for my mental maths.
Let's see… If I've got 30 USD running total, then I estimate a 20% total tax... No, let's do it as 25%. That'd be around 37.50 USD with the tax estimate. Doing it as 20%, it should be around 36 USD.
Doing the calculation with 17.5% via a calculator, it is 35.25USD. Doing it with 20% seems to be close enough, 25% a bit too much. But that depends on what's the total tax percentage--or if it even works that way. It's something I'm too unamerican to understand.
It's honestly not that hard to memorize your times tables. You do it once in third grade and it stays with you for life.
I use it daily, personally. Comes up a ton in gaming. How many of these can I afford? Etc.
Chess is a good one. No calculator allowed. You have six minutes to make 9 moves, how many seconds per move? And don't take too long because the calculation eats into your time.
Oh, I grew up during the time where calculators were actually forbidden even in Trigonometry exams (we were provided the necessary values along with the exam questions, or a table of sines/cosines/tangents). So yeah, it reinforced my knowledge of arithmetic (by basically forcing me to use it again and again).
And indeed, as I've mentioned in a top-level response to the thread, I've basically have my times tables (up to 10--because that's what I was taught) memorized. I can recall it within a couple of seconds.
However, mental arithmetic usually just gets used when I estimate stuff. Mostly with groceries, but sometimes for estimating travel times. For example, if I left at 14:00, reached the midway point at around 15:15, I'd estimate I'd arrive at around 16:30, add a bit of leeway and say I'd arrive around 17:00.
360 seconds in 6 minutes. Make 9 moves → 40 seconds per move. I actually took a few seconds realizing that 6 minutes = 360 seconds tho (went with 5 minutes = 300 seconds, 6 minutes = 300 seconds + 60 seconds).
I also just work it out in my head. There are certain "landmark" numbers and tricks that I use to save time. For example, 9 times any number is easy: multiply by 10 and subtract once. x11 is similar. Same with anything close to a perfect square. (7 x 8 = 7 x 7 + 7)
I think that memorization was important to achieve speed before phones/calculators. Nowadays, I would consider memorization an obstacle to understanding.
As a teacher, no, memorization is an important step before understanding. I do agree thought that in the times before memorization was a bigger emphasis, but that's because it was understood that the only information you'd have easy access to would be what youve memorized since we didnt have the internet. Now we teach kids in Literature class how to vet their sources because they are all exposed to the misinformation vortex.
I think a lot of the backlash against rote memorization is the rote part. Without understanding what you're memorizing—treating the times table as a list of sequences (times table for 2, and then 4, and then 5, etc), the mental load memorizing it becomes unbearably high.
In my case, I was lucky enough to have been made to understand what's going on (4 groups of 8 items = 40) before being asked to memorize the times table. The visualization also helped me memorize, as well as some tricks (what's 6×7? 6×6 = 36, right? add 6 to arrive at 42) that as I memorize more and more of the table, become less and less necessary.
Memorization of key facts is required for the development of higher reasoning. For example you can not understand global trade if you have not memorized basic geography.
Key facts, sure. If you don’t know geography, no amount of reflection can provide you with the location of Hong Kong.
However, i can figure out anything on the 12x12 timestable in a few seconds, no memorization needed. I don’t even need the landmark numbers that i mentioned because multiplication is just repeated addition. The only things i had to memorize were the numerals and the operators.