To ask if you do long multiplication/division regularly?

[BoyTree]

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?

Yes, constantly; I think I’m an outlier on here. I find it much quicker to grab a piece of paper and do it then put the numbers into a calculator (including true long division sums such as 7843 divided by 96) or to do multiplication in my head. I can do stuff like 5642 x 38 in my head faster than putting it into a calculator.

As a disclaimer - I LOVE maths. I sit and play with maths in my spare time. I’m a maths teacher. I teach my A level students to do long division with algebra. I suspect I am not representative!

Errol It's the method, the maths not the arithmetic, which matters.

Or as my now late Director of Studies used to say 'don't worry about the 2s'.

@CherryPavlova I see I’m not the only one who finds it quicker in my head!

I find it easier to do lots of sums on paper and spread them out (so I can see the answers) than do them on the calculator and remember earlier answers/what I'm doing.

(Although I kicked myself during my dissertation when I figured out a visual way of doing what I wanted in excel that had taken me days to do by hand)

I do long multiplication in my head (badly) sometimes when I can't sleep. I can't actually do long division any more so never do.

I found the "but I will never use this after the exams so whhhhhyyyyyy do I need to learn it now" complaint tedious 20 odd years ago when I was at school and am no more sympathetic to it now. I used to know the periodic table- have I ever needed to know it since GCSEs were over? Have I bollocks, but the methods of learning and remembering it have certainly come in useful throughout my life. Has thinking about what Ibsen was saying in A Doll's House ever got me a job or helped me balance my household budget? No, but it enriched my life and again, helped me develop a way of thinking about and looking at things that has definitely been of benefit.

I don’t use maths in everyday life. I really don’t

One of the most stupid things I've ever read, are you 13?

@Iggly

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.

Not sad at all! Start with completing the square method of solving quadratics and use that to solve :-

ax^2 + bx + c = 0

Good luck!

@hansgrueber

I don’t use maths in everyday life. I really don’t

One of the most stupid things I've ever read, are you 13?

Most people probably don't though. Maybe a bit of basic algebra but beyond that, nope.

I don’t use maths in everyday life. I really don’t

Really? Do you not budget or think about how much your grocery shopping is costing? Whether its worth driving a little further to the cheaper supermarket? How much you need to put by in savings, how much money you should have spare for spending after covering essentials?

Whether its better to sign up to the £40 a month for 2 years mobile phone contract or buy the phone outright for £599 and get a £10 a month sim only for the data service?

How much you need to change the recipe by because you need to use a smaller cake tin or feed an extra person?

How much paint you need to buy to paint a room when the coverage is X m2 per litre and your room is 4 m x 5 m x 2 m tall?

Whether its worth paying for a season ticket compared with paying £Y per visit.

I do.

I work in an office and will frequently do it by hand. Tbf I'm a mathematician, and quite enjoy it.

If I'm looking at invoices, and it doesn't look right, I'll do an approximation to the sum, and if I still don't think it's right I'll do an accurate sum.
I do it for finding area of rooms (so 6.87m x 3.45m) and calculation of whether it's worth buying in bulk of 36 or 24 etc.

So yes, I do, however I do like working on paper with figures. Would very rarely get a calculator out.

Do kids get taught how to do approximations nowadays? I can't remember it being 'taught' but that might be my memory - iirc it was what people with some sense of numbers worked out how to do for themselves, along with various shortcuts.

@ErrolTheDragon

Do kids get taught how to do approximations nowadays? I can't remember it being 'taught' but that might be my memory - iirc it was what people with some sense of numbers worked out how to do for themselves, along with various shortcuts.

Yes they do. But less capable ones forget to use it to check the 'sense' of their answers.

I play around with algorithms when I’m working because stopping to look at a different screen (calculator) breaks my chain of actions. Sometimes I use long multiplication in my head as it’s quicker easier and more interesting.

I can still do it, and sometimes do if there's a pen and paper closer than my phone or a calculator.

I also taught a niece and 2 nephews how to do it, because they were struggling and didn't understand it, despite having been taught it recently in each case.

@UrAWizHarry

Never, I have this device called a calculator.

I've never needed to work out the diagonal of a farmer's field having inexplicably measured the other 2 sides either.

Ah, but you will have found that knowing how to would have made some things in life more easily achieved!

Will that ladder reach the sofit?

Will my 32" tell fit the space I have for it? (remembering that tv measurements are always the diagonal).

More uses if you play a field sport, or sail, orienteering, general navigation.

I've never needed to work out the diagonal of a farmer's field having inexplicably measured the other 2 sides either

But you might need to know how much wider a 48" TV is than a 40" if you have a certain space it needs to fit into (clue, it's not 8 inches for the reason specified by Curious).

My ds has A at A level maths and has a gold certificate senior maths challenge and never got long division

@BarbaraofSeville

I've never needed to work out the diagonal of a farmer's field having inexplicably measured the other 2 sides either

But you might need to know how much wider a 48" TV is than a 40" if you have a certain space it needs to fit into (clue, it's not 8 inches for the reason specified by Curious).

And I'd find out by looking up the measurements online. Or measuring the length of the side I actually cared about in the first place.

If farmer Bob has the means to measure his field and only cares about the diagonal of the field, it would have been faster to measure the 1 diagonal rather than the two sides.

(Was it not clear I was being flippant?)

Me! This sort of grounding in maths provides the foundations and building blocks to more intelligent maths useage later on. How important this is to your son depends on where his aspirations lie. If his dream is to be something very practical like an engineer, architect, surgeon, banker, accountant, coder, or to run his own business then he needs to put away the calculator and get his brain to do the work.

I also find mental maths useful for general life - mortgages, managing money, doing the accounts. It’s far quicker than a calculator and your brain will pick out errors more easily. Of course people get by just fine without it but I find it useful.

Definitely useful in architecture and engineering. Sometimes it’s quicker than getting a calculator. Also, it’s really important to be able to work it out in your head so you can get a feel for the numbers and spot mistakes intuitively.

I would say a solid understanding of GCSE level maths is really important in my field. I don’t use A-Level maths now, but it helps to be comfortable with numbers and practice makes perfect - it’s a life skill and he won’t regret learning it

I use long multiplication occasionally, just to make sure nothing has gone wildly wrong with calculations done in Excel or on a calculator. Can't remember how to do long division, but am going to relearn it today as a result of this thread!

And I'd find out by looking up the measurements online. Or measuring the length of the side I actually cared about in the first place. Relying on someone else to give you the answer. Might not be possible for some items!

If farmer Bob has the means to measure his field and only cares about the diagonal of the field, it would have been faster to measure the 1 diagonal rather than the two sides. Have you ever tried measuring the diagonal of a large area? As long as it is vaguely rectangular it is far easier to measure 2 sides... pace it out etc.

(Was it not clear I was being flippant?) No. It becomes more clear that you haven#t given the topic sufficient thought though [lighthearted etc etc ]

It doesn't matter how likely he will need it in life. There are lots of basic skills and knowledge that machines and internet now do it for you. Is he refusing to kick a football or learn a 2nd language because they aren't essential for survival ?
I would say treat it as a challenge, a not-too-difficult one in fact, and an opportunity to practise perseverance.

I have a Physics degree and a Statistics postgrad, I run my own business and I never do long division or almost any mental maths now. I have never been good at it (I have dyslexia so poor working memory) and I always have my smartphone to hand, which is far quicker and more reliable. I do use maths all the time though, in my work and every day life, but I always use a calculator to do the calculations.

We bought a corner desk online once. It gave the width and depth of the table when sat at it, but not the dimensions you would need to know if it would fit along the wall...