Expert: Josh - 9/8/2008

Question
                             -rt
When using the formula P=Ae            how is it entered on  the scientific calculator
          
            -0.08(2)
ex. 10,000e           =10,000(0.852143789)=$8521.44

How do you get 0.852143789

Answer
Hi Helen,

It depends on what type of calculator you are using. It is common nowadays that formulas are punched into the calculator literally in the order they are written.

If we look at the equation P=A*exp(-r*t), where A=10000, r=0.08 and t=2, you can try:
10000 [*] [exp] [(] [-] 0.08 [*] 2 [)] [ans]

Here, anything other than digits, I use square brackets to represent buttons.

In order to access the exponential function, you may need to first press the [shift] key before hitting [exp] to accomplish this. Go with the feedback you see on the LCD display to see if you've got things right. One simple check is to try [shift] [exp] 1 [ans] if it returns 2.718281... you are on the right track. This is the most common approach. If you see the word "exp" written as superscript above one of the button, that is the button you want to press following the shift key. It varies from model to model. Some calculators label the [ans] button as [enter], again you get the drift.

The older generation of calculators does not show the entire expression as you type (only the digits you punched in and reveals intermediate answers when you hit [ans]); they rely on the user in getting the syntax right. The way to deal with this is to solve the most complicated part first, and work your way out from the deepest nesting of brackets (i.e., inside out). To avoid things getting overly complicated, the user can store intermediate values in memory and use the recall facility (consult with the calc. menu).

Example:
[-] 0.08 [*] 2 [ans] [exp] OR
0.08 [minus] [*] 2 [ans] [exp]
should return the value of "exp(-0.08*2)"

then, I would press
[*] 10000 [ans]

Using the memory function, here is an idea:
0.08 [plus or minus] [*] 2 [ans] [exp] [shift] [memory in] [1]
then,
10000 [*] [shift] [memory out] [1] [ans]

I can't say with any certainty because each manufacturer overloads the functions with regular buttons in a different way.