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HP Forum Archive 05

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HP-12C Rounding of periods
Message #1 Posted by Hoang Tran on 4 Mar 2001, 9:37 p.m.

Is there any way I can get the calculator to give me fractions of periods rather than having it round to the next highest period?

Here is an example:

Invest $1000 at 10% annual interest. How long does it take for the the money to double? The HP will say it takes 8 years, although it really only takes seven years and change. How do I get this value displayed as 7.xxx?

Thanks,

Hoang.

      
Re: HP-12C Rounding of periods
Message #2 Posted by Todd Garabedian on 5 Mar 2001, 8:55 p.m.,
in response to message #1 by Hoang Tran

You can change the number of decimal places by pressing "f" followed by a number equivalent to the number of decimal places. For example, pressing f4 gives four places after the decimal.

Pressing "f" followed by "." and then followed by a number gives scientific notation.

Hope that helps.

Todd

      
Re: HP-12C Rounding of periods
Message #3 Posted by Les Bell (Australia) on 5 Mar 2001, 11:37 p.m.,
in response to message #1 by Hoang Tran

Hoang Tran wrote:

>> Invest $1000 at 10% annual interest. How long does it take for the the money to double? The HP will say it takes 8 years, although it really only takes seven years and change. How do I get this value displayed as 7.xxx? <<

Problem here is your selection of compound interval. Although the interest rate is 10% per annum, it is more usually compounded monthly, i.e. i = 10%/12 = 0.83%. Now, if you repeat the calculation, you should get a result of 83.52 *months*, or just under 7 years. I would expect the 12C to have shifted functions to allow entry of annual interest rates, but compounded monthly - the various 41C pacs that do TVM all do.

Best,

--- Les [http://www.lesbell.com.au]

            
Won't work. HP12C ALWAYS rounds "n" UP
Message #4 Posted by Gene Wright on 6 Mar 2001, 10:59 a.m.,
in response to message #3 by Les Bell (Australia)

The HP12C always rounds the value of N up to the next whole integer.

The HP12C owners manual (or application manual) has a program that can be keyed in to provide a more "accurate" answer, but the stock HP12C cannot do this.

Gene


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