Question

users
#1

I haven't done much spread sheet formula work so please don't mind a couple
of simple questions.

I would like to do two things:

1. Calculate compound interest on an amount given the rate and number of
interest periods. Looking at the list of functions there are lots of ones
that come close to that, but I wasn't able to find one that would do exact
that.

2. How do I write a conditional loop in Calc? If I want to calculate a
formula for 10 iterations how would I do that? For instance
Value=Value*N+Value. That would give me the compound interest also. I can do
it with a bunch of cells strung out each one representing one interest
period, but for any length of time it becomes unwieldy.

Thank you very much for any help.

Cliff

#2

I've had troubles in the past finding specific financial functions, as well. Can't help from the function standpoint in this case, but you could always fall back on the actual equation:

FV = PV*(1+i)^n

where FV is future value, PV is present value, i is the periodic interest rate, and n is the number of periods.

Dave

#3

** Reply to message from Dave Liesse <dsliesse@liessefamily.net> on Wed, 27
Nov 2013 16:12:16 -0800

Dave,

Thank you for the formula! I figured out how to enter it as a user function
so it's easy to use. Thanks again.

Cliff

#4

https://wiki.openoffice.org/wiki/Documentation/How_Tos/Calc:_FV_function

#5

Now that Dave was kind enough to translate the problem into common financial terms I recognize, finding the FV function is easy.

Menu->Insert->Function->Select Financial->FV
OR, use the function wizard to accomplish the same.

I've always hated word problems, I could never translate words into math equations. But the OP asked about calculating compound interest which is not the same as future value. Calculating FV is definitely an important first step.

This link: http://www.ehow.com/how_2166243_calculate-compound-interest.html shows the same formula Dave provided (albeit Dave's formula was much more helpful), but they go the extra step of showing that the compound interest is actually the Future Value minus the Present Value.

I had to scratch my head over this a few times and re-read the link quite a few times before I finally saw the answer sitting there in front of me. They calculate the interest on $1000 in the example link - show that FV = 1210, and finally show that the interest ends up being the FV of $1210 minus the original PV of $1000: so interest earned is $210.

I would never have recognized the formula in the link as being FV, and so without Dave's help I couldn't have figured any of this out.

#6

** Reply to message from A <publicface@bak.rr.com> on Fri, 29 Nov 2013
20:45:54 -0800

Now I see how the existing FV would do what I needed to do. What threw me was
that it says to enter a payment value which there is none except the interest
accrued. Reading the info on the Wiki page explains that one can use 0 as the
payment then get the value including the compound interest. It would be very
helpful if the Help file included that key bit of information. I was
surprised that LO didn't have what would be a common financial function, but
in fact it did, I just didn't recognize it.

Cliff