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#1 2013-11-10 10:29:03

SuperLynx
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Percentage of a Number ?

How do I calculate the percentage, one number taken away from another number; here is an example:

2345-1278 = 1067

What would be the percentage ?

#2 2013-11-11 03:22:22

bobbym

Online

Re: Percentage of a Number ?

Hi;

Percentage of what to what?

The 1067 to the 2345?

Or do you want the percentage reduction?

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#3 2013-11-11 03:34:00

SuperLynx
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Re: Percentage of a Number ?

If I told you \$2345 and you told me you only wanted to pay \$1067 how much percentage would you want off, would that be the same as what you mentioned 45.5% ?

Last edited by SuperLynx (2013-11-11 03:34:22)

#4 2013-11-11 03:51:43

bobbym

Online

Re: Percentage of a Number ?

Subtract 2345 from both sides.

Divide both sides by - 2345.

You get .5449893390191898. So you would need a 54.49893390191898% reduction.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#5 2013-11-11 04:15:47

SuperLynx
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Re: Percentage of a Number ?

If you subtract 54% from 2345 you get 1266.3 not 1278 ?

.54% that is a decimal, hrmm

Last edited by SuperLynx (2013-11-11 04:18:02)

#6 2013-11-11 06:24:02

bobbym

Online

Re: Percentage of a Number ?

54% is not the correct answer that I gave you.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#7 2013-11-11 11:28:43

SuperLynx
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Re: Percentage of a Number ?

I never said that was the correct answer you gave me ! <sigh>

I wanted to know where you got the decimal .54 from ?

2345-2345 obviously gives you 0 yet you say it gives 1067 ?

If I subtract 1278 from 2345 I get 1067

1278 / 2345 = .54

Are you saying that if you wanted to pay only \$1278 from the original price of \$2345 that would be a .54 or 54% cut ?

#8 2013-11-11 17:43:56

bobbym

Online

Re: Percentage of a Number ?

I never said that was the correct answer you gave me ! <sigh>

You are missing what I am saying. 54% is not the answer I gave you, you have rounded off the correct answer.

Post #4, that is where the 54.49893390191898% is coming from. If you keep doing your calculations as 54% you will have an error.

Are you saying that if you wanted to pay only \$1278 from the original price of \$2345 that would be a .54 or 54% cut ?

Nope, I am not saying any of that. First of all where do you get 54% from? I am saying if you take a 54.49893390191898% reduction you will come out with 1067 ( a number very close to it!).

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#9 2013-11-12 01:25:08

SuperLynx
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Re: Percentage of a Number ?

You get .5449893390191898. So you would need a 54.49893390191898% reduction.

That is where I'm getting the 54 !

#10 2013-11-12 01:28:49

bobbym

Online

Re: Percentage of a Number ?

It is not 54, it is 54.49893390191898 %.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#11 2013-11-12 01:48:46

SuperLynx
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Re: Percentage of a Number ?

I'm rounding as you said, when you round it's 54 !

#12 2013-11-12 01:52:41

SuperLynx
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Re: Percentage of a Number ?

2345 - 54% = 1266

A little off from 1278, but close.

#13 2013-11-12 01:53:37

bobbym

Online

Re: Percentage of a Number ?

I never said to round in the calculation.

bobbym wrote:

That was just for convenience. If I were speaking that I would say about 45%. But in a calculation if you use a number that you say is about this then the answer is rounded also. That is why you are getting 1266.3 not 1278.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#14 2013-11-12 01:56:58

SuperLynx
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Re: Percentage of a Number ?

2345 - 45% = 1289

I don't understand what you meant
>>>That was just for convenience. If I were speaking that I would say about 45%. But in a calculation if you use a number that you say is about this then the answer is rounded also. That is why you are getting 1266.3 not 1278.

#15 2013-11-12 02:00:13

bobbym

Online

Re: Percentage of a Number ?

2345 - 45% = 1289

The above statement is incorrect and in math correctly stating the problem is the difference between solving it and not solving it. You can not subtract 45% from 2345. You can subtract 45% of something from 2345.

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#16 2013-11-12 02:04:56

SuperLynx
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Re: Percentage of a Number ?

You can't subtract 45% from 2345, you can subtract 45% of something from 2345, show me an example !

#17 2013-11-12 02:08:14

bobbym

Online

Re: Percentage of a Number ?

If I get 45% off that is the decimal .45

If I get 54.49893390191898 % off that is the decimal .5449893390191898

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#18 2013-11-12 02:13:51

SuperLynx
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Re: Percentage of a Number ?

2345 - .45 what is that multiplication symbol after that, all I see is a dot ?

#19 2013-11-12 02:16:29

bobbym

Online

Re: Percentage of a Number ?

The dot between the .45 and the 2345 means multiply. It can also be written,

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.

#20 2013-11-12 15:33:37

SuperLynx
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Re: Percentage of a Number ?

bobbym wrote:

The dot between the .45 and the 2345 means multiply. It can also be written,

Doing the above math always gives me 5497969.75 not 1289.75

#21 2013-11-12 20:32:24

anonimnystefy
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Re: Percentage of a Number ?

That's because you are doing subtraction before multiplication. When there are no parenthesis, you do multiplication before addition and subtraction.

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

#22 2013-11-12 21:35:20

phrontister
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Re: Percentage of a Number ?

Many calculators, particularly scientific calculators (eg, M\$oft's scientific calculator), will automatically do the operations in the correct order (BODMAS) without needing to use parentheses, but simpler calculators (eg, that same M\$oft calculator set to the 'Standard' option) usually won't.

For key presses "2345-.45x2345":
M\$oft Scientific = 1289.75
M\$oft Standard = 5497969.75

With my HP32SII RPN Scientific the key presses are:
2345
Enter
.45
Enter
2345
x
-

"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson

#23 2013-11-12 21:51:49

anonimnystefy
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Re: Percentage of a Number ?

Reverse Polish notation?

The limit operator is just an excuse for doing something you know you can't.
“It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman
“Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment

#24 2013-11-12 22:18:25

phrontister
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Re: Percentage of a Number ?

Yes...which my HP48SX Scientific has too.

"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson

#25 2013-11-12 22:41:33

bobbym

Online

Re: Percentage of a Number ?

Doing the above math always gives me 5497969.75 not 1289.75

One problem at a time. Do you understand the percentage we are talking about?

In mathematics, you don't understand things. You just get used to them.
I have the result, but I do not yet know how to get it.
All physicists, and a good many quite respectable mathematicians are contemptuous about proof.