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AIBU?

Share your dilemmas and get honest opinions from other Mumsnetters.

Original poster

To ask if you do long multiplication/division regularly?

223 replies

BoyTree · 10/12/2020 15:34

Please settle a debate for me!

Older son is doing long multiplication and it came up that it would have been more important to know the formal 'method' to complete the sum by hand/brain when calculators weren't so ubiquitous. He asked who would still be doing it by hand now and I was stumped!

I can't think of anyone who would routinely do long multiplication using the column method as part of their job, but felt sure I was probably overlooking some vital role. Does anyone here use it or know of a job where this skill would be vital?

OP posts:
ErrolTheDragon · 10/12/2020 22:31

Rarely, other than order of magnitude approximations which I probably do quite a lot without really thinking about it. And now I've got an Apple Watch I've literally always got a calculator to hand.Grin

Someone mentioned matrices upthread... it's a heck of a lot easier to write a bit of code to multiply them than to do it by hand.

hansgrueber · 10/12/2020 22:37

@MissPollyPops

I don't ever do it. Wouldn't remember how to. Actually, don't think I was ever taught long division...
There was a thirty year or more gap, 70s to 00s, when it was unfashionable to teach tables, long multiplication/division, grammar etc., I once heard a Head telling his wife off, she was a secondary teacher but doing supply in a primary school, she had been teaching tables!
hansgrueber · 10/12/2020 22:42

@Macncheeseballs

I dont do it often but am glad I can if i wanted
It's about self-respect, I don't use it much now I've retired for teaching Maths, but I'd hate to think I couldn't do it. I will quite often do the oddest Mathematics, just for fun, I once woke at 3am and decided to prove the formula for solving quadratic equations from first principles!
lazylinguist · 10/12/2020 22:44

Never. I can, but I never need to.

Scarby9 · 10/12/2020 22:52

I do it whenever I have acalculation that requires it. I would do it long hand rather than reaching for a calculator.

HallFloor · 10/12/2020 22:56

I do if I only need one calculation and the calculator isn't to hand, but I realise most people would use their phone.

Iggly · 10/12/2020 22:58

I once woke at 3am and decided to prove the formula for solving quadratic equations from first principles

Is it sad that I want to teach myself how to do this again 😂 I was shit hot at maths and loved this sort of thing.

Not needed now. I’m an accountant though and do occasionally work things out instead of using a calculator or excel.

DrCoconut · 10/12/2020 23:04

I teach engineering maths at levels 4 and 5 so this would be our start point, but important to have the basic skills. I'm always astonished by adults who finished school but can't add up a shopping bill or work out a 15% discount. These are simple things the same as being able to read, not the witchcraft that people believe it is.

lanthanum · 10/12/2020 23:11

I think long multiplication and long division are no longer relevant, and I'm a maths teacher. Nobody does it in real life, because you either use a calculator, or do it mentally using "chunking methods" (like when you split a restaurant bill in your head). I very occasionally do it by hand, but that's because I'm sufficiently good at it that the effort is less than going to find my phone or a calculator - but for younger generations, that's unlikely to be the case.

There is a use for long division when teaching A-level students to divide polynomials, but I don't think that's enough to justify making everyone learn it. In fact, I never taught long division with all the remainders worked out underneath (like the year 6 tests demand); I got students to jot down the times table for the number they were dividing by, and then work the remainders out in their head.

NoIDontWatchLoveIsland · 10/12/2020 23:11

Never do it, nope. My job is very numbers driven but I can't think of a time when I haven't had a calculator or excel sheet to hand.

DramaAlpaca · 10/12/2020 23:12

I do both regularly. I like to keep my brain sharp.

JaceLancs · 10/12/2020 23:12

Don’t do it - but still can
The most my current job requires is simple maths - if not too lengthy I prefer not to use a calculator but I’m 50+ and was taught with log tables and slide rules
I always quite liked maths as there were no variables!

SisyphusDad · 10/12/2020 23:13

I have a very numerate role with a lot of ad-hoc calculation. Rather than use a calculator or Excel I often do one-off calculations by hand just to keep my brain sharp.

BabyofMine · 10/12/2020 23:14

I have a really basic call centre job but because it’s in the financial services sector still need these skills. Sometimes your computer is acting up/frozen whilst on a call and it’s quicker to just work something out than put the customer on hold and keep them waiting. So it’s really, really not just high paid or really well-respected jobs where things like this come in handy.

chomalungma · 10/12/2020 23:16

I think estimating an answer is an incredibly useful thing to be able to do.

But long multiplication and long division - not something that I do lots of.

BabyofMine · 10/12/2020 23:17

Also, I find Ianthanum’s post really really depressing that even a maths teacher doesn’t see the point.

ErrolTheDragon · 10/12/2020 23:20

I always quite liked maths as there were no variables!

That sounds quite funny to someone who writes mathsy codeGrin

chomalungma · 10/12/2020 23:21

@BabyofMine

Also, I find Ianthanum’s post really really depressing that even a maths teacher doesn’t see the point.
It's not that useful.

Most people have a phone on them that can do calculations if their computer can't do it.

jessstan1 · 10/12/2020 23:21

@mindutopia

Nope, I couldn’t do it in school and still can’t do it now. Teacher said I was so bad at maths that I’d probably never finish school. Hmm This was said to me when I was in about year 6.

I have a PhD now. Still can’t do long division though.

I can't do long division either!
ErrolTheDragon · 10/12/2020 23:26

Most people have a phone on them that can do calculations if their computer can't do it.

Surely every computer (and tablet) can do simple arithmetic (and unit conversion) - just type it into the browser search bar.

Jux · 10/12/2020 23:27

I use if often just being alive.... I did quite a lot working out the capacity of our pond and then how much medicine I should drop in there to deal with a sick fish. It was fun.

Anyone in my family will ask me to do sums - balancing books, planning disposition of furniture, all sorts.

I have a little spreadsheet regarding COVID, another about daytime temperatures since about 1870 I think (no official records back then), a few spreadsheets about wool.......

chomalungma · 10/12/2020 23:29

@ErrolTheDragon

Most people have a phone on them that can do calculations if their computer can't do it.

Surely every computer (and tablet) can do simple arithmetic (and unit conversion) - just type it into the browser search bar.

It was more if their computer wasn't working (as in 'whirring' round)

Browsers are great.

Saoirse7 · 10/12/2020 23:32

It's not necessarily the skill of being able to do it mentally - rather the understanding of how it is done so the method can be applied to other similar equations.

FangsForTheMemory · 10/12/2020 23:34

I do long division occasionally. If it’s one or two sums, I can do it quicker on paper than on my phone.

ChestnutStuffing · 10/12/2020 23:36

I have at times, not at the moment.

If you know your math facts it's not that difficult to do it, so why bother with the calculator? And even if you are using a calculator, you want to have a sense of whether the answer you are getting seems right, or you won't spot errors.

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