Can anybody remember how to do long division ?

Fr0dders

Fr0dders

Fr0dders

Caporegime
Joined
18 Oct 2002
Posts
33,467
Location
West Yorks
I'm helping my missus with her NVQ at the moment, and she has to express 80 as a precentage of 1,880. This is easy on the calculator as its 80 divided by 1880 which is 0.0425 x 100.

Question is. how do i do this as long division ? i can do it where the answer is greater than 1 no problem ! but when the answer is 0.0425 or whatever is where im struggling.

I havent done this since i finished school years ago and its driving me mad. Long division should be for 11 years old but ive forgotten it all. Help !
 
Umm it's been a looong time i remember there was this squiggle where the number being divided went on top and the number dividing went in front...

*grabs some paper*
division.jpg


That looks about right... hopefully the steps make it obvious how I did it.
 
Last edited:
I used to be dead good at it but now can't remember a thing. It was one of those nuts things you did at school that you never have to use in the real world. Short division is the usual way. Or a calculator.
 
I could do it, but it'd be a mare to layout on this forum, and I don't have a scanner to hand.

If you're still stuck this evening when I get home, I'll do it on paper and scan it in for you.
 
I could do it, learn it at primary school when i was in Hong Kong, its not difficult, you just got to know your times table.
 
This simplifies neatly as 80/1880 = 8/188 = 4/94 = 2/47

47|2 [read 47 into 2] 'doesnt go' so write a 0 above the 2, and put .0 after the 2
47 into 20 also doesn't go, so write a second zero next to the first on the top line.

now we have 47|2.00 with 0.0 written above the 2.0, to determine the next digit consider 47|200 which goes 4 times with a remainder of 12, so write 0.04 on the top and add another zero to the bottom row. Our remainder was 12, write this in superscript before the zero we just added, so with this zero we now consider 47|120

This goes twice with a remainder of 26. So we write a 2 on the top line, which has now got to 0.042, and the remainder of 26 is written in superscript as before, directly before another zero appended to the lower line.


47|260 goes 5 times with no remainder, as soon as we get no remainder we are finished.
This 5 is appended to the top line, so
0.0425 is the answer.


It occurs that possibly all you needed to know was to write a decimal point after the 1880 and a second directly above this one, then add zero's onto the bottom and proceed as before. I also need to learn how to format posts I think, 47|2.0 should have a horizontal line above the 2.0

Hope that helps a bit :)


edit: so, so conclusively beaten to that response
plus I got 260/47 = 5, which isn't great given I'm meant to be an engineer
 
Don't forget it is a percentage not a straight divide.


To express x as a percentage of y the general rule is..

x multiplied by 100 divided by y

or

x/y multiplied by 100

or

x multiplied by 100/y


whichever helps most - it is ll the same. ie 100x/y

so your question becomes 80/1880 times 100

just looking at it, clearly the answer is around 4%, so applying the stuff in JonJ678's post you can get the exact number.

80 x 100 /1880
8000/1880
800/188
400/94
200/47

So the long division to give the answer in percent would be 47 into 200 (unless I made a silly mistake somewhere).

Incidentally - a tiny nit-picking point about JonJ's post - 5 * 47 = 235 not 260 so there are a few more places of decimal to go. 260 divided by 47 is not 5 with no remainder.

When using a calculator watch how many decimal places you have set it up to show you. Same with excel spreadsheets.
 
Last edited:
M'eh ok so I got the method right but put the answer below not on top... I knew something didn't look right!
 
JonJ678 said:
This simplifies neatly as 80/1880 = 8/188 = 4/94 = 2/47

47|2 [read 47 into 2] 'doesnt go' so write a 0 above the 2, and put .0 after the 2
47 into 20 also doesn't go, so write a second zero next to the first on the top line.

now we have 47|2.00 with 0.0 written above the 2.0, to determine the next digit consider 47|200 which goes 4 times with a remainder of 12, so write 0.04 on the top and add another zero to the bottom row. Our remainder was 12, write this in superscript before the zero we just added, so with this zero we now consider 47|120

This goes twice with a remainder of 26. So we write a 2 on the top line, which has now got to 0.042, and the remainder of 26 is written in superscript as before, directly before another zero appended to the lower line.


47|260 goes 5 times with no remainder, as soon as we get no remainder we are finished.
This 5 is appended to the top line, so
0.0425 is the answer.


It occurs that possibly all you needed to know was to write a decimal point after the 1880 and a second directly above this one, then add zero's onto the bottom and proceed as before. I also need to learn how to format posts I think, 47|2.0 should have a horizontal line above the 2.0

Hope that helps a bit :)


edit: so, so conclusively beaten to that response
plus I got 260/47 = 5, which isn't great given I'm meant to be an engineer
Click to expand...

gotcha

something like this ?

longdivision.jpg
 
Manual long division was always a pain - especially if you made a mistake and went on calculating and calculating and calculating when it should have worked out cleanly ages before.

Anyone remember using logarithms and antilogarithms to "simplify the process? We also had to learn to use slide rules - do they even make those anymore?
 
You must log in or register to reply here.
Back
Top Bottom