doing a maths night class, can any one in simple terms explain to me:

[dissle]

How to do percentages,
How to turn a fraction into a percentage and back?
How to do subtraction...yes really, i absolutely struggle and get a different answer each time i do them.

How to turn a fraction into a decimal number.

there HAS to be an easy way to do and remember these things.

gentle guide to percentages here

this site is helpful

For the suntraction think, how much less is the second number,

so 10-7=

How many less is 7 than 10? 3

10-7=3

20-10=

How many less is 10 than 20?

OH MY GOD>>>Perfect martian, thanks SO much...added it to my favourites, will keep doing it...

a million thankyous xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

with subtractions its the.....468
-376
that i struggle with, dont ask me why i just seem to get a different answer every time i do it. ??????

I could teach you subtraction dissle, (primary school teacher - must be able to teach that sort of subtraction in my sleep!-but not here - too complicated!

Do you use the borrowing technique? ie in your example, you can take 6 from 8 but get stuck when you get to the tens column as you can't take 7 from 6. You need to borrow a hundred from the hundred's column so you actually have 16 tens and take 7 tens from them. Then, your hundreds column only had 3 in the top number and 3 in the bottom which cancel each other out.

Told you it is complicated to explain here but dead easy to explain in person!

LOL! Dumbledore...you're allot of use!

No still dont get it, just looked at the website more closely, dont understand where the numbers come from?????

for the 468-376 example dissle round up or down the numbers to benchmark your answer

468-376 is rougly 470-380=90
so you know to expect an answer around 90

a percentage is a proportion of 100

• so 50% is 50/100 (50 out of 100) - which can also be written 0.50 or 1/2
• 85% is 85/100 or .85

4/5 is the same as 80/100 or .8 or 80%

If you don't have a calculator then you need to say - what do I have to multiply the bottom by to get to 100 (in the example above 5x20=100), then multiply to top number by that too (so 4x20=80), then you have 4/5 is the same as 80/100 which is 0.8 or 80%

With substractions - add the answer you get to what you subtracted and you should get back to the original number (as a check)

so 85-43 = 42 42+43 = 85

any help ?

I do use the borowing method, yes.
I get confused when carrying over though...dont know where to add it IYSWIM

rounding up i can do, makes it easier in fact, you can then get an aproximation cant you...great for multiple choice questions.Thanks whichchips

OOOH Throcky, yes that makes sense, just let me have a go on a few by myself....see if i can get it..

another way (without the borrowing)

468-376

(460+8)-(370+6)

(460-370)+(8-6)

90+2=92

another way to do substraction - eg 468-376

start at 376 - how many do you have to add to get to 468 - so you need 2 to get to 8, -10 to get from 70 to 60, and 100 to get from 300 to 400, so add them together 2-10+100=92

check 92 + 376 = 468

468
376-
--

first take 6 from 8= 2

You cab't take 7 from 6, becayuse 7 is bigger than 6.

You borrow one from the next column along, and make the 7, 17 (because the next colum along is 10 time bigger, so 1 from there = 10 IYSWIM)

You can now take 8 from 17= 9

Beause you borroed one you have to pay it back, and you put that on the bottom and add that on to the 3, which makes it a 4. 4-4=0

468
376-
1
-
092

trying to do 63% except i cant work out what goes into 100 and what goes into 63 to cancel down.
Help?

LOVE that way wichychips, that is so easy.

think my way is easier

63%=

63

100

so its 63%= 0.63
or63/100, how do you make it smaller tho?

It has to be divisible to make it smaller

eg 50/100 is the same as 5/10

so 63 is divisble by 3 (3 x 21 = 63)

Howeever as 100 isn't divisible by 3 you can't use it (or would be 21/33.333333 which is not nice!)

63%=63/100

63 has no "common factors" with 100
so 63/100 can't be simplified

common factors = whole numbers that be divided into both numbers
so 2 is a common factor of 4 and of 8

another example
65%=65/100
common factor = 5

65/5 = 13
100/5 = 20
65/100 = 13/20
13 has no common factors with 20 so stop

witchandchips said it much better than me!

ahhh thats why i couldnt do it..brilliant! thanks.

so its the number which will divide into both numbers. BUT it has to be divisable or you just leave it alone...is that right?

you can't, because 63/100 is 0.63

you can make a fraction smaller if you can divide the top and bottom numbers by something, and end up with a whole number answer

so 10/100 is the same as 1/10 (you can difide them both by 10). And both of these are 0.1