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?

I did say "most".

If they don't then it is invariably place value that has eluded them. This can take years to sink in. I by no means expect all of them to get it and some will stick with grid, partitioning or whatever gets them the answer. But for whatever reason it is part of the year 6 curriculum (even though they continue to do it for the next three years.....)

I myself took maths gcse at night school as an adult after failing the o level I took early at 13 and losing my confidence so I know a bit about the pitfalls. In over 24 years of teaching though, the vast majority can and will get it.

If they can understand that you are multiplying by both tens and ones you can get there. If they don't have the place value understanding then the placeholder means nothing and you are better off using other methods.

Just to clarify for those who have mentioned it - he isn't refusing to do them and he does see the benefit of being able to do all kind of mathematical stuff, it was purely a debate as to whether there are jobs that require the skill any more in the way that it would have been essential for an endlessly wide range of roles before digitisation.

I think the problem is that he likes to work things out for himself, so he would happily complete the calculation himself using his own weird and wonderful method, which yields the correct result most of the time but takes longer than following the column method.

So the debate was mostly about needing to quickly complete this kind of calculation in a situation where using a calculator/phone/computer wouldn't be appropriate or possible.

Part of me wants to encourage him to think about the ways that the numbers interact and use the methods that he finds most intuitive rather than learning a 'method' which can be followed without requiring any real understanding of how you are actually 'building' the correct answer.

He's not at school, so we were wondering if there was a reason to learn the column method over his own calculations or whether to let him find his way a bit more on the assumption that he'll be able to pick up the method more easily later.

Thanks to all those who have replied - it's been really interesting reading about people who do maths for fun as my son is already leaning towards that and I find it fascinating that he can be sitting there looking utterly gormless and then I discover he's been doing maths in his head!

Tradition. Really pupils should be encouraged to find a method that works for them. That they get. If the grid method works for long multiplication then fine.

I have seen a pupil do 37 *15 by doing 37 15 times in a column and i don't think that's good though.

I did say "most". I was only replying about those that don't!!

If they don't then it is invariably place value that has eluded them. Invariably!!! I could tell you tales of Math Misery that would make your hair stand on end! I have no idea why school funding streams don't allow teachers time and space to help those significant minority that don't become comfortable, let alone capable with maths. Especially as they, the government, are continually increasing what the minimum acceptable is, piling on the pressure to get a C grade at GCSE, even stating that C grade is not good enough (Goviotness at its best/worst).

I do it all the time for work. I prefer it to using the calculator.

Curious, it makes me furious. We cram our year 6's, they then have little new learning and far less maths weekly for 3 years. I would far rather align the two curriculum sensibly so we could do less in year 6 and embed more.

My ds scraped expected in SATS and has sat below ever since. He's not "5" candidate so he's badically left to languish and I can see him being forced to take it again and again. It could be so different for him if we just taught maths differently across primary and secondary.

We do 1.5 hours a day in year 6. We use manipulatives, song, games, formal and informal methods and do LOTS of mental arithmetic every day. I know the children inside out and understand their barriers. I can address them in registration
time and pre-teach before hometime for the next day. Then they go to secondary. They get 3 hours a week with maybe two or 3 different teachers, very little if any practical, and it's all more or less the same co tent as year 6 bar a tad more algebra. There must be a better way to do it.

Where I work, we aren't allowed mobile phones, so I have to use longhand maths there. It's reasonably common - changing units for example

At home, I've been doing lots of renovation, and I always do long division/multiplication to get a ball-park figure for buying supplies. Can't be assed to look for my phone when I've got pen and paper there.

Re columns - if he has his own way, could it be that he has some sort of understanding of numbers behind what he is doing? I use columns cos numbers are meaningless to me.

@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).

Many people buy flat pack furniture, assemble it on the floor then find there isn't enough ceiling height to stand it up! That's Pythagoras for you. We had movers who took a wardrobe upstairs, lay it on its side and couldn't stand it up, when I suggested that they put it onto it's back then lifted it they didn't believe me A calculator is only as good as the person pressing the buttons, you often need a bit of mathematics. A salesman was reducing a few items by 22.5%, he was tediously doing 'price x 22.5 /100' writing it down then doing 'price - answer'. He was amazed when I suggested that he do 'price x 0.775'.

Only when I teach it. Painful lessons.

Long division in particular I think is pointless. The primary curriculum requires children to divide by any 2 digit number - why?? Dividing by numbers to 12, fine, they are supposed to know those tables. Multiplying by a 2 digit number, I get, and it’s easily taught - to x47 you x40 and x7 and add together. To divide by 47, you have to first work out your 47 times table. I don’t see purpose to 11 year olds doing this. In real life surely you’d use a calculator. I say this as a primary maths teacher 😂

Totally agree with the poster above that we cram too much in the primary and then they repeat it all at secondary anyway. I’d ditch a lot of the fractions objectives, some of the geometry, long division, conversion to imperial units (whhyyyyyyy) and a few other bits from y5/6 and really embed the other stuff instead. Far too much content, not enough time to teach it.

conversion to imperial units (whhyyyyyyy)

There's still a lot around - including (with some differences) US measures. That's one of the more useful to laypeople type of maths.

There's still a lot around - including (with some differences) US measures. That's one of the more useful to laypeople type of maths.

Aviation related job..used to regularly have to look at figures in US gallons and convert to litres or better still kilograms..there were tables/apps etc available but the ability to at least grasp the conversions and get some feel for the credibility of what was going on was darned important..

Here's why..

en.wikipedia.org/wiki/Gimli_Glider

Not in my current role, but as a staff nurse I did drug calculations using long multiplication and division (e.g. a medication is provided at x mg per litre and you need to administer y mg to the patient, how much do you give).

I never realised that about tv size! I assumed it was the width not the diagonal. TIL

All the time. Cooking, when making things. It's a basic life skill.
I would hate to have to depend on a device to be able to work these things out for me.

For those who say teaching it is painful, the montessori maths and geometry material for 6-12 year olds is BRILLIANT.
They start off with the stamp game, (I love this!) there is the chequer board and racks and tubes.
Triangles sets and yellow surface material for geometry.
Senatorial learning makes so much sense before moving onto abstract concepts.

Never. I just use my phone. Rubbish at maths and I can't even remember how to do long division.

Can't do it, don't use it and if I need it, I have a calculator
My maths teacher once told me that I was too dumb to be there so why bother, that was the last day I attended a maths class, I was in yr 8.
My teacher also said we won't always have a calculator with us, oh how wrong they were lol

I have a maths PhD, but am largely incapable of doing anything involving numbers. I'm always puzzled when people say that being good at arithmetic is an essential precursor to understanding more complex maths, because that is absolutely not my experience (I do understand how long division works, of course, but to actually do it would take me ages).
I think that the obsession with learning set methods to perform calculations very depressing - and actually a sign of a very dumbed down education system that values procedural fluency over an understanding of the underlying structure and an ability to tackle unfamiliar problems.
I hated maths at primary school, but as soon as I got to Secondary School the fact that I couldn't add up stopped mattering, and maths became about logic, puzzles and patterns - I got the highest mark from my O level board, and never did get to grips with my times tables.

Yes sometimes

In my head. At times I might note down half of the sum

I can not do long division on paper but I can in my head or my own way on paper

And I subtract by counting the difference

Ds is the same he always gets the answer right but constantly told to show how he worked it out (he too finds this difficult)

I do it every couple of days cos it's quicker than finding my phone

I also do it on paper when I can't be bothered to get out the calculator (or in my head).
I've done it for knitting (each repeat is 18 stitches, how many repeats in the whole pattern) and cooking (65g per person, how many in total) as well as for work (what SHOULD my spreadsheet say).
I do use repeated adding, and simple multiplication then times 10 or 2, as well.

Can't quote as on the phone. Doing long division for drug calculations can get complicated. 46 mg per ml and you need 730 mg. Much easier to divide 730 by 46 with a calculator and know the answer should be between 10 and 20 ml than use a long written method where you have to do several steps where a mistake could happen.

I have done the previous calculation doing chunking and formal long division. For both methods I needed to know that 5 x 46 is 230. I also needed to subtract. I think chunking is a lot easier to grasp than formal long division and it reinforces division as simply the opposite of multiplication and you can use multiplication facts to work out the answers.

You appear to have posted (2) twice.