[rogluu]

trying to do some math percentage questions with my playbook but i get the wrong answer, if i try to do 1+50%, i get the correct answer, 1.50, but if i try to do 2+50%, i get 2.50, am i typing it wrong?

[aft1981]

Yes you are typing it in wrong.

50% = 0.5 as a decimal

Therefore you typed in 1 + 0.5 = 1.5 and 2 + 0.5 = 2.5

[Tom-Z]

It seems the playbook calculator treats % in an odd way. The sign just represents division by 100. So 1 + 50% = 1 + 50/100 = 1.5 but 2 + 50% = 2 + 50 / 100 = 2.50.
Solution: if you want to get 2 plus 50 percent of 2, type 2 * 150%.

Arguably even having a % sign on any calculator is a crime since there is no unambiguous way of defining it.

[rogluu]

yea, i guess i will have to do the number *1.5

[kmcobra64]

the playbook calculator treats percent like any other calculator. "per-cent" means division by 100 by its very definition. If you put in 1+50%, a calculator does not know that your intention is to add 50% of 1 to itself. It treats 50% as what it is: 50/100. Try this out on any standard calculator, you will get the same result.

Posted from my CrackBerry at wapforums.crackberry.com

[peter9477]

Haven't tried it myself on the PB, but on calculators in the past the percent thing was always more useful with multiplication... So 2 * 50% would produce 1, and 2 * 150% would produce 3.

If the PB is doing that as well, I agree it's acting exactly like calculators generally do.

[ferganer]

in order to get 250% of X you need to type 2*X + X*50%. that's standard on most calculators.

[CiderGuru]

that's standard on most calculators

I'm afraid it isn't...

Playbook:
2
+
50
%
=
(Display Shows) 2.5


Windows XP:
2
+
50
%
(Display shows) 1
=
(Display Shows) 3


Blackberry7:
2
+
50
%
(Display Shows) 1
=
(Display shows) 3

My desk calculator:
2
+
50
%
(Display shows) 3

[ferganer]

I'm afraid it isn't...

Playbook:
2
+
50
%
=
(Display Shows) 2.5


Windows XP:
2
+
50
%
(Display shows) 1
=
(Display Shows) 3


Blackberry7:
2
+
50
%
(Display Shows) 1
=
(Display shows) 3

My desk calculator:
2
+
50
%
(Display shows) 3

Now, try entering 2+2*50%. All your calculators should give you the same result. You may have to enter 2+(2*50%) or 2+2*(50%) depending on how your calculator processes order of operations ("Please Excuse My Dear Aunt Sally" ), but it's the same principle.

[CiderGuru]

Now, try entering 2+2*50%. All your calculators should give you the same result. You may have to enter 2+(2*50%) or 2+2*(50%) depending on how your calculator processes order of operations ("Please Excuse My Dear Aunt Sally" ), but it's the same principle.

Sorry, quoted the wrong person. I was saying that whilst most calculators handle percentages the correct way, as indicated by my examples, a few older ones do not. The PlayBook does not either.

[leticeberry]

Why don't they fix it to make it like regular calculators? So I have to use a regular calculator to find out of my Playbook calculator is correct? If I wanted to figure 2+50%, why can't I just type in 2+50% to get the correct answer? I hope they fix this.

[ferganer]

Why don't they fix it to make it like regular calculators? So I have to use a regular calculator to find out of my Playbook calculator is correct? If I wanted to figure 2+50%, why can't I just type in 2+50% to get the correct answer? I hope they fix this.

I have 4 of the most often used calculators (both scientific and financial, e.g. TI-30XIIS) at home and neither gives 2+50%=3. All give 2+50%=2.5. So the PB calculator at the very least does the same thing as most standard calculators.

[FF22]

Why don't they fix it to make it like regular calculators? So I have to use a regular calculator to find out of my Playbook calculator is correct? If I wanted to figure 2+50%, why can't I just type in 2+50% to get the correct answer? I hope they fix this.

Obviously, I'm not a mathematician but I don't understand your equation. Nor do I use calcs that much.

As I read it, it is 2 PLUS something. But what is 50%? The 50% stands alone, so 50% of what is being added to 2? What is being added to the 2? I gather calcs have their way of dealing with entries.

[RohrohrohURboat]

Interesting points of view. I'd like a solution for this.

I have not seen a basic calculator that the % button converts a number to a decimal.

If I wanted to add 50% on to a value of 2, I would input 2 + 50 [%] which would then show the answer of 3 not 2.50 .

This is supported by the calculator on my desk, computer my BB9900 and every other BB I've used, except my playbook.

It is a bit frustrating.

[kmcobra64]

Interesting points of view. I'd like a solution for this.



I have not seen a basic calculator that the % button converts a number to a decimal.



If I wanted to add 50% on to a value of 2, I would input 2 + 50 [%] which would then show the answer of 3 not 2.50 .



This is supported by the calculator on my desk, computer my BB9900 and every other BB I've used, except my playbook.



It is a bit frustrating.

Ok, the fact that your calculator does it as some type of shortcut does not make it mathematically correct. The playbook is correct, and here is why:

Addition is commutitave, meaning that 2+3 yields the same answer as 3+2. This is the same for any values when added together.

Based on this fact, 2+50% should equal the same value as 50%+2. But if you do these two calculations on one of these calculators that you deem "correct," you will find that the former gives you a value of 3, while the latter gives you a value of 2.5. According to mathematical laws this is incorrect and impossible.

What a calculator should do, and what the playbook does, is read your input as 2+(50/100). Any calculator that does not yield 2.5 is providing you a shortcut, but is not correct mathematically. As an engineer it drives me crazy when I see this because it makes the calculator unpredictable. You expect the calculator to do math the way math is done and not provide unexpected "shortcuts".


Sent from my BlackBerry 9930 using Tapatalk

[hackerguy]

From a math point of view it is best to always think of % as a shorthand way of referring to the decimal equivalent of the number. That is how it is used in calculations. Calculators that handle it otherwise (in my opinion) only contribute to the serious lack of mathematical skills so evident in society.

[RohrohrohURboat]

Why does the Calulator on my 9900 operate differently to the playbook?!?!?

[peter9477]

This is obviously one of those discussions that could be religious. Best to simply call it ambiguous...

Quick: "two plus fifty percent"... what's the answer?

There is no single right answer, other than maybe asking "fifty percent of what?"

Some designers have chosen to interpret that in one way (50% of the value immediately before the plus sign) while others have chosen a different approach (50% of unity) and other interpretations are possible (e.g. maybe 50% of the results of the formula entered so far if you were to hit "=" now).

There's no solution that serves both groups without adding a setting to control it.

The setting should probably be set for the convention used most widely by the audience, which I'm guessing would be "50% of previous value" gang. An ugly alternative might be to have a dialog pop up the first time the % key is used in that way, educating about the issue and asking what the user would prefer. Yuck...

[ryansmithknowsbest]

I hate mqth

[cleacy]

I have 4 of the most often used calculators (both scientific and financial, e.g. TI-30XIIS) at home and neither gives 2+50%=3. All give 2+50%=2.5. So the PB calculator at the very least does the same thing as most standard calculators.

I just tested that on a TI-BA II Plus (it's one of the two financial calculators approved for use in accounting and actuarial certification exams).

2
+
50
% (display now reads 1)
=
3

[kennyliu]

I just tested that on a TI-BA II Plus (it's one of the two financial calculators approved for use in accounting and actuarial certification exams).

2
+
50
% (display now reads 1)
=
3

I just checked this on my TI-30XIIS and I get 2+50%=2.5.

[ralfyguy]

I just checked this on my TI-30XIIS and I get 2+50%=2.5.

Same on the PB

[TheScionicMan]

"Hey, this isn't a Wizard, it's a Wilard"

[kmcobra64]

This is obviously one of those discussions that could be religious. Best to simply call it ambiguous...

Quick: "two plus fifty percent"... what's the answer?

There is no single right answer, other than maybe asking "fifty percent of what?"

Some designers have chosen to interpret that in one way (50% of the value immediately before the plus sign) while others have chosen a different approach (50% of unity) and other interpretations are possible (e.g. maybe 50% of the results of the formula entered so far if you were to hit "=" now).

There's no solution that serves both groups without adding a setting to control it.

The setting should probably be set for the convention used most widely by the audience, which I'm guessing would be "50% of previous value" gang. An ugly alternative might be to have a dialog pop up the first time the % key is used in that way, educating about the issue and asking what the user would prefer. Yuck...

The fact of the matter is: there is ONLY one right answer. If you do not specify 50% of something then 50% = .5

This is the great thing about math. There is NO interpretation, NO debate, NO opinions, just the right answer, and everything else is wrong. This is why math is a universally understood concept. Any calculator that does not treat a stand alone 50% as .5 is trying to create math shorthand. The problem that this creates can be seen by the fact that there are threads like this now where people just assume 2 + 50% should = 3 simply they have a calculator designed by an english major who thought they were smarter than the laws of math.

I dont mean to attack you personally peter, just quoted you because you mentioned that there is no one right answer, while in reality, there is.

[kennyliu]

The fact of the matter is: there is ONLY one right answer. If you do not specify 50% of something then 50% = .5

This is the great thing about math. There is NO interpretation, NO debate, NO opinions, just the right answer, and everything else is wrong. This is why math is a universally understood concept. Any calculator that does not treat a stand alone 50% as .5 is trying to create math shorthand. The problem that this creates can be seen by the fact that there are threads like this now where people just assume 2 + 50% should = 3 simply they have a calculator designed by an english major who thought they were smarter than the laws of math.

I dont mean to attack you personally peter, just quoted you because you mentioned that there is no one right answer, while in reality, there is.

What's also strange is that, if you enter 2+50%= into Wolfram Alpha, it gives you 3. Those guys should know better that this is not correct.