1.  07/30/2009, 11:47 AM Turns out the Pre's built-in calculator is dumber than a 3rd grader. Every third grader knows that 5% of 100 is 5. Every calculator I own (desktop calc, my old Treo, iPod Touch, etc.) performs the following function properly: 100 + 5 % = 105 The Pre thinks: 100 + 5% = 100.05 I got an idea... let's tell Palm's software team that their raises are gonna be calculated on the Pre's calculator. Think it might get fixed in an update? ----- Be sure to read post #24. The point was to use a simple example to show how the Pre's calculator delivers an unexpected result, NOT that I have a problem coming up with a way to actually calculate percentages. In spite of the many flames and replies offering advice on how to use the calculator to accurately perform the calculation, that was never the point. Last edited by larnapp; 07/31/2009 at 04:34 AM. Reason: People missing the point
2.  07/30/2009, 11:51 AM Um...... what? 100 * .05 = 5 which is correct (5% of 100). What are you talking about? It looks like you're using the modulus operator which doesn't exist on the calculator. What is the exact formula you're using because it sounds like user error.
3.  07/30/2009, 12:00 PM Originally Posted by Kasracer Um...... what? 100 * .05 = 5 which is correct (5% of 100). What are you talking about? It looks like you're using the modulus operator which doesn't exist on the calculator. What is the exact formula you're using because it sounds like user error. First of all, the Pre calculator DOES have a "%" key. It appears when you press the spacebar. So... I enter 100, then the plus key, then 5, then the spacebar (to access the % key), then the % key, then the equals key. No user error. Try it.
4.  07/30/2009, 12:04 PM % is an operator that divides by 100. That is correct. What you are wanting is the original plus 5 %. The long way it is 5% of 100 + 100. The "of" operator is always multiplication. This works: 5 % x 100 + 100 = 105 The original is 100%. So 100% x 100 + 5% x 100. Or summarized to 105% of 100. 105 % X (of) 100 = 105 So this issue here is that with 100 + 5%, the calculator doesn't know that you are taking a percentage of 100. The problem is that the 100 is queued up to be added to and has nothing to do with the % operator. This is a limitation of a non-RPN calculator, but not a "bug". I would never try to use the calculator that way. Just seem odd. The % operator is simply to convert a number to a percentage. 5 becomes 0.05. It is a unary operator, and so happens before the binary operator of the +. This seems correct to me. You added 100 to 5% (or 0.05). That is indeed 100.05. User error is the verdict for me as well. When operators are included in weird orders, the calculator can only do exactly what you told it to. Last edited by sacherjj; 07/30/2009 at 12:17 PM.
5.  07/30/2009, 12:04 PM OK but 100 + 5% doesn't make any sense. So the Pre calculator must be ignoring the '%'. You could say 5% of something. But adding 5% to something just doesn't make any sense. If what you really want is to say 100 + (5% * 100) (100 + 5% of 100) then you need to key in 100 + 5% * 100. Or if you were the 3rd grader in your example you would probably already know that 5% is 0.05 so you could type 100 + 5 * 0.05. Hence, USER ERROR!!!
6.  07/30/2009, 12:05 PM Sorry, buddy. The calculator is correct. 100 + 5% (or + 0.05) does indeed equal 100.05 ... DUH! 100 x 5% = 5 (You must multiply, not add) 100 x 5% + 100 = 105
7.  07/30/2009, 12:05 PM Okay then, so it does have a %. That still doesn't change the fact that it's a modulus operator and NOT a percentage. It's still user error.
8.  07/30/2009, 12:06 PM 5% = .05 What third grade did you go to?
9.  07/30/2009, 12:11 PM No comment from OP? *crickets* I guess google is wrong as well. 100 + 5% = 100.05
10.  07/30/2009, 12:13 PM Originally Posted by ejohnnyk Sorry, buddy. The calculator is correct. 100 + 5% (or + 0.05) does indeed equal 100.05 ... DUH! 100 x 5% = 5 (You must multiply, not add) 100 x 5% + 100 = 105 Okay. You said "DUH so I must be stupid. But seriously, go find ANY calculator, enter 100 + 5% and see what you get. Here's one: Calculator - Metacalc 100 + 5% = 105 every time.
11.  07/30/2009, 12:13 PM LOL! The Pre's calculator is right. 100 + 5% is equal to 105% or 1.05.
12.  07/30/2009, 12:14 PM ROFL
13.  07/30/2009, 12:16 PM Originally Posted by Kasracer Okay then, so it does have a %. That still doesn't change the fact that it's a modulus operator and NOT a percentage. It's still user error. % isn't a modulo operator on the Pre; it is a "per cent" operator and it functions as expected. Not, of course, as you expected. Take a look at this page. It explains why the "%" key operates the way it does. www dot mathleague dot com/help/percent/percent.htm Ugh. Post count too low to post a real link.
14.  07/30/2009, 12:18 PM damn my brain hurts.
15.  07/30/2009, 12:19 PM Originally Posted by Kasracer Okay then, so it does have a %. That still doesn't change the fact that it's a modulus operator and NOT a percentage. It's still user error. The meaning of % is defined by context. In this context, % actually means percent, its original meaning before it was re purposed for modulus.
16.  07/30/2009, 12:19 PM the pre is just doing the percent first, 100 + (5%) = 100.05 100 + (.05) = 100.05 seems logical order of operation to do when parsing a equation. At least that's what i would do. Thinking the other calculators are just wrong or don't have an advanced algorithm for parsing equations, although pre's calc is pretty simple. If i remember i'll try it on my Ti 89 when i get home see what she does.
17.  07/30/2009, 12:20 PM Originally Posted by neile45 LOL! The Pre's calculator is right. 100 + 5% is equal to 105% or 1.05. No it is actually equal to 100.05 or 10,005% 100% + 5% would be 105% or 1.05.
18.  07/30/2009, 12:25 PM Besides all this smart people talk...as soon as you press the % key it changes ur 5 to .05 Did you not look while you typed?
19.  07/30/2009, 12:26 PM lol this is too good
20.  07/30/2009, 12:27 PM Originally Posted by ajk511 Besides all this smart people talk...as soon as you press the % key it changes ur 5 to .05 Did you not look while you typed? +1
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