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Homework Help: Calculator issues?

  1. Feb 25, 2012 #1
    1. The problem statement, all variables and given/known data
    To save money you put $3000 at the end of each year in an annuity that pays 6.8% compounded annually. Use the formula for the value of an annuity.
    The Given Formula:
    Code (Text):
    How much would be saved at the end of six years.

    2. Relevant equations
    The Variables:
    Code (Text):
    The Completed formula:
    Code (Text):
    When i put this exactly into http://web2.0calc.com/ (because im without a scientific calculator at the moment)

    3. The attempt at a solution

    My Final Answer Is: A=44102.945538271292235294118
    Rounded To The Nearest dollar: A=$44103
    The program I Am Submitting The Answer To Says, the answer is: A=$21352 rounded to the nearest dollar.

    My question is why is my answer wrong, is it the calculator? do i have a parentheses out of place?

    EDIT: fixed spelling errors and a few minor changes, none involving the math.
    Last edited: Feb 25, 2012
  2. jcsd
  3. Feb 25, 2012 #2
    after about an hour of crying and an hour of raging that no1 would reply i figured out the mistake it was a parentheses
  4. Feb 25, 2012 #3


    Staff: Mentor

    So it was the missing parents around the (1)(6) factor right?
  5. Feb 26, 2012 #4
    nope, it wasn't, even tho that would have been another issue if my post was completely honest i actually multiplied them together before i put it in the calculator, the issue was the (1+(.068/1)^(1)(6)) should have been ((1+(.068/1))^((1)(6)))
  6. Feb 26, 2012 #5
    in other words, add the 1 to the fraction before the exponent
  7. Feb 26, 2012 #6

    What I do to reduce the number of parentheses for that part in the
    calculator display and make it relatively easier to read is type:

  8. Feb 26, 2012 #7
    well from my time spend in my programing classes i must have completely forgotten how to debug, i have become too reliant of others help and need to seriously look at the problem before asking for help. on the most basic level, there are more just remove the outter most set of parenthesis until you see the problem lol
  9. Feb 26, 2012 #8


    Staff: Mentor

    Why do you show division by 1 and multiplication by 1? Instead of 1 + .068/1, why not write 1.068? And instead of 1*6, why not write just 6?
  10. Feb 26, 2012 #9
    I was emphasizing an intermediate step where it is common for some beginning
    calculator users to enter a product incorrectly. I was allowing for a denominator
    other than 1 and a larger product for the exponent by my example.**

    For myself, I would actually enter it they way you asked about for
    [i[that problem[/i], because I know that is even simpler and I can
    do that in my head.

    ** Example:

    P(1 + 0.068/12)^(12*17) is what I would type for a different example
    with relatively more difficult arithmetic.
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