Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I have a formula in an excel spreadsheet that calculates compounding interest over a period of time in 20 different cells, reducing the amount in each increment using the following formula:


This code generates a linear decrease across the period directly from point a to point b.

What I am trying to do is have a field that can determine a curve based on how quickly payments are made up front?

i.e. Currently displays like this enter image description here

And now I want a field to enter a number which determines that curve:

i.e. Entering 100 might do this (i.e. repay 100% more each increment ): enter image description here

NOTE: I want the number (100) to be adjustable to change the view of the graph

share|cite|improve this question

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.