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## #676 2013-03-20 03:24:39

SteveB
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Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

Right OK. Percentages.

Now, if I have a number like say 50 and you had to add 10% would you know how to do that ?

(I am trying to get an idea of how much you know already)

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## #677 2013-03-20 03:30:54

mandy jane
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Registered: 2010-09-23
Posts: 1,132

### Re: Mandy Jane's Corner

no i do not know how to do that ok? so now want?

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## #678 2013-03-20 03:37:31

SteveB
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Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

Right. OK. Now I will give you a worked example for that. Some people reading this would know at once the answer, but
I will explain how I would think about this question (in a way that works when the numbers are not quite so nice).

The percentage 10 %  can be thought of as being like the decimal 0.1
If you say "calculate 10 percent of" something then you mean calculate  0.1 times something.
In other words we are trying to work out 50 x 0.1  and then adding that to 50.

So I happen to know that  50 x 0.1 = 5
So that means that  10% of 50 is in fact 5

Then when you add that on to the number 50 you get  55

Now are you happy with the concept of multiplying by a decimal like 0.1 ?

Can you see that if you multiply by 0.1 you are dividing the number by 10 ?

EDIT:

Last edited by SteveB (2013-05-09 07:15:53)

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## #679 2013-03-20 03:42:02

mandy jane
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Registered: 2010-09-23
Posts: 1,132

### Re: Mandy Jane's Corner

yes i think i understand? can you make sure please?

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## #680 2013-03-20 03:44:15

SteveB
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Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

Right here is a related question to test you on multiplying by a decimal:

What is  20 x 0.2 ?

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## #681 2013-03-20 03:52:36

mandy jane
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Registered: 2010-09-23
Posts: 1,132

### Re: Mandy Jane's Corner

no i looked at it again and no i don't understand it at all ok?

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## #682 2013-03-20 04:00:35

SteveB
Member
Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

When I look at the number 0.2 I would automatically know that it is one fifth, but that is not necessarily obvious.

You can re-write 0.2 as a fraction by the fact that it is the same as 2 tenths.

So using some Latex:

Last edited by SteveB (2013-03-20 05:30:08)

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## #683 2013-03-20 04:04:36

SteveB
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Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

I will have to try to get better at using Latex. I am struggling with using it to write fractions.

Right now: Here is another question .....  What is one fifth of 20 ?

So what is  0.2 x 20 ?

What is  20 %  of  20 ?

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## #684 2013-03-20 04:10:57

mandy jane
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Registered: 2010-09-23
Posts: 1,132

is it 22then?

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## #685 2013-03-20 04:11:43

SteveB
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Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

Okay here are a few notes on that:

one fifth of 20 is:

Last edited by SteveB (2013-03-20 05:31:52)

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## #686 2013-03-20 04:13:45

SteveB
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Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

Have you been taught about multiplying fractions ?

Last edited by SteveB (2013-03-20 07:41:48)

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## #687 2013-03-20 04:15:04

SteveB
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Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

What whole number is the fraction ....

equal to.

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## #688 2013-03-20 04:19:17

SteveB
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Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

Okay the answer is that 20 should be divided by 5.  The answer is four.

That is to say:

Any number divided by 1 is itself.

Therefore:

Last edited by SteveB (2013-03-20 05:35:09)

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## #689 2013-03-20 04:21:32

SteveB
Member
Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

20 % can be thought of as the same as the following fraction:

Try cancelling or simplifying this fraction as far as you can go. What do you get ?

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## #690 2013-03-20 04:23:41

mandy jane
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Registered: 2010-09-23
Posts: 1,132

### Re: Mandy Jane's Corner

to answe 686 no i have not been taough multiply fraction i don't think?

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## #691 2013-03-20 04:36:32

mandy jane
Member
Registered: 2010-09-23
Posts: 1,132

20
---
100

2
---
10

1
---
5

am i right?

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## #692 2013-03-20 04:37:58

SteveB
Member
Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

Sorry about that my computer crashed so it then wasted several minutes rebooting.

I think we had better discuss multiplication of fractions. This is relevant to percentages to a certain extent.

Right let us take an example:

The answer is to multiply top and bottom numbers together....

So the numerators (top) are  2 x 1 = 2
The denominators (bottom) are  3 x 2 = 6

So the result is:

This simplifies to:

Last edited by SteveB (2013-03-20 05:37:32)

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## #693 2013-03-20 04:41:11

mandy jane
Member
Registered: 2010-09-23
Posts: 1,132

### Re: Mandy Jane's Corner

ok could i have som fraction for me to do befor tomorrow ok?

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## #694 2013-03-20 04:41:25

SteveB
Member
Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

Your post # 691 is correct. Good. Well done. I will give you a chance to read the next post.

Last edited by SteveB (2013-03-20 05:38:12)

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## #695 2013-03-20 04:47:23

SteveB
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Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

Right I will give you a few fraction multiplication problems. Remember not to confuse adding and multiplying fractions.

Cancel or simplify as far as possible.

(At the time of posting I was unable to use Latex to display things like this in a good readable fashion
I have now been taught by Bob to do this properly. If you look further back, Mandy, you will find that
I have gone through it and tidied up the earlier fractions. They will hopefully be easier to read.)

Last edited by SteveB (2013-03-20 05:46:44)

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## #696 2013-03-20 04:47:41

mandy jane
Member
Registered: 2010-09-23
Posts: 1,132

### Re: Mandy Jane's Corner

did you read post 693 if so do you have an answer for me?

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## #697 2013-03-20 04:53:46

mandy jane
Member
Registered: 2010-09-23
Posts: 1,132

### Re: Mandy Jane's Corner

see you at 2.00pm on here tomorrow by

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## #698 2013-03-20 04:53:55

SteveB
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Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

Another quick question for you to answer:

Last edited by SteveB (2013-05-09 07:21:35)

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## #699 2013-03-20 05:14:45

bob bundy
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Registered: 2010-06-20
Posts: 7,548

### Re: Mandy Jane's Corner

hi SteveB and Mandy

Here is a way to improve your Latex.

http://latex.codecogs.com/editor.php

Bob

Last edited by bob bundy (2013-03-20 05:22:19)

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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## #700 2013-03-20 05:54:04

SteveB
Member
Registered: 2013-03-07
Posts: 577

### Re: Mandy Jane's Corner

Mandy I recommend that you look through this entire page again I have updated some of my posts to improve readability.

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