It finally happened, the day I've been dreading since the birth of our first child

stickyfiddle

Phil_aka_Pip said:

stickyfiddle said:

I have a flipping maths degree and I say long division is pointless and unnecessary and it saddens me that they still teach it.

Isn't that a bit like saying we don't need to teach boolean algebra because everybody works at FPGA or VLSI level? or that gear-shifting & clutch control is unnecessary because of automatic gearbxoes?

I don't know what those things are.

In any case, my point is that regular long division isn't a very good algorithm for solving division problems, but also it doesn't particularly help explain the logic of *why* 161 divided by 14 is 11.5 or whatever.

As many have said, the important thing is to understand the nature of division and multiplication and then you can do anything.

It's like giving the man the fish rather than teaching him how to fish, except you're telling him go to the beach in a specific place and use a specific fishing line and fish will randomly appear on the end of the string, when you could instead show him that fish live in the sea and if you get a boat and a net you can go wherever you want across the sea and catch loads of fish whenever you want to.

stickyfiddle

Phil_aka_Pip said:

But learning how to manipulate them is part of appreciating how they work. Otherwise it's like giving people pictures of scale patterns on a guitar without letting them play them on a real instrument.

I'd say it's more like teaching endless scales without letting the kid listen to Led Zepellin...

lloyd

Col_Decker said:

equalsql said:

The worst part of it is that they no longer teach them traditional long division so you have to learn a different and IMHO  inferior system.
You're gonna love that

^ this

 

The method she is using is, for example, if you're dividing 296 by 7, first you work out the multiples of

1 x 7

2 x 7

5 x 7

10 x 7

20 x 70 then subtract it from the 296 in stages and add up the factors you used (ie 1 x, 5x, 20 x).

 

FFS

I've read that twice and don't understand it or why you'd do that...was different in my day I tell ya

Phil_aka_Pip

Give a man a fish and he will eat. Teach him to fish, and he will sit in a boat and drink beer all day.

Col_Decker

lloyd said:

Col_Decker said:

equalsql said:

The worst part of it is that they no longer teach them traditional long division so you have to learn a different and IMHO  inferior system.
You're gonna love that

^ this

 

The method she is using is, for example, if you're dividing 296 by 7, first you work out the multiples of

1 x 7

2 x 7

5 x 7

10 x 7

20 x 70 then subtract it from the 296 in stages and add up the factors you used (ie 1 x, 5x, 20 x).

 

FFS

I've read that twice and don't understand it or why you'd do that...was different in my day I tell ya

OK you asked for it so here goes ... 296 / 7

first write out this:

1*7 = 7

2*7 = 14

5*7 = 35

10*7 = 70 

20*7 = 140

 

then see which is the biggest number that goes into 296. In this case its 140 (20*7). Then subtract 140 from 296:

 

296 - 140 = 156 and put '20' in brackets (from the list above):

156 (20)

 

 

then repeat using 156 as the new number, whats the biggest number from the list that goes into 156? Its 140 again, so subtract 140 from 156 and put another 20 in the brackets)

156-140 = 16 (20,20)

 

then repeat

 

whats the biggest number to go into 16? Its 14 (2*7)

 

16-14 = 2 (20,20,2)

 

you can't divide the remaining 2 by 7 so that's your remainder.

Then add up the numbers in the brackets: 20+20+2 = 42

plus the remainder 2 = 42.2

 

 

simples ... err

stickyfiddle

Col_Decker said:

equalsql said:

The worst part of it is that they no longer teach them traditional long division so you have to learn a different and IMHO  inferior system.
You're gonna love that

^ this

 

The method she is using is, for example, if you're dividing 296 by 7, first you work out the multiples of

1 x 7

2 x 7

5 x 7

10 x 7

20 x 70 then subtract it from the 296 in stages and add up the factors you used (ie 1 x, 5x, 20 x).

 

FFS

WTF?

You just say..

no sevens fit in 2, so carry the 2 to make 29.

4 sevens in 29, with 1 left, so carry that to make 16. The 4 here actually represents 40 because we're in the tens column

2 sevens in 16 and 2 left over, so add 2 to your 40 and you have a remainder of 2 to either stop there or keep going to get your decimals.

lloyd

Fair enough it now makes sense but I don't know why you'd do it like that...I'll stick to the old fashioned way (calculator).

ToneControl

Countdown stylee?

Phil_aka_Pip

@stickyfiddle's method is what I was taught. makes sense, shows the concept of dividing the dividend by the divisor. ie tells you what division is about. whereas the other method doesn't

mike_l

Long division is easy. Get Mrs Decker to explain it to Decker Jnr.

shuikit

Recently had to go through this with my little brother who was doing it some really bizarre way.  I had to do a bit of googling and ask a mate who's a teacher to get it.  I think the intention behind learning all different methods is good and in theory at least will help kids have 'a feel' for numbers.  But what I found the problem was that the method was just taught old, just follow this procedure way rather than teaching the why it works so some kids can get a bit confused and unsure to which one to use etc.  I wonder, if in my brother's case if the teacher themselves fully understood the method....

I've been led to believe that in secondary school they'll either get taught to use one method or they won't mind which method is used as long as they get the correct answers!

Col_Decker

Phil_aka_Pip said:

@stickyfiddle's method is what I was taught. makes sense, shows the concept of dividing the dividend by the divisor. ie tells you what division is about. whereas the other method doesn't

Aye ... garage method

vasselmeyer

I got through my entire time at school, right through to sixth form, without ever knowing how to do long division manually. I'm not proud of it, but I have to say, I don't feel I've missed a big part of my life because I can't do it.

mart

ToneControl said:

....
I'd have thought that long division and using log tables are not really much use now. ....

This. Division is hugely important. Even more important is understanding it as inverse to multiplication. Knowing the precise technique of long division is of no use whatsoever. I can do a huge amount of mental arithmetic without recourse to a calculator, and I would never use long division.

Long division* is as useless as being able to use log tables. 

*of integers. Long division of polynomials is hugely important. Well ok, maybe only if you're a professional algebraist.

holnrew

Give it 11 years when she brings me home to meet the family.

chillidoggy

I know how to do long division.

EricTheWeary

Col_Decker said:

chillidoggy said:

Col_Decker said:

 

 

 

 

Is that some kind of hurdy-gurdy, folky thing?

That young whipper snapper is a mechanical calculator. They we all the rage for us late '70s early '80s maths wizzes. Pre Mr. Sinclare natch

isn't it a comptometer?

ToneControl

chillidoggy said:

I know how to do long division.

I've pretty much forgotten, and I'm supposed to be a mathematician. Can't remember doing anything like that at Uni

Siri does my basic arithmetic now

hungrymark

Phil_aka_Pip said:

Trad. long division works. teach her that and sod what the educational experts say.

Yeah, always a good idea. Bloody so-called 'experts' who know what they're talking about.

chillidoggy

I don't use long division these days, though. Like everyone else, I use a calculator. But the kids should know how to do it, IMHO.