The Motley Fool Discussion Boards Previous Page Investing/Strategies / Retirement Investing URL:  http://boards.fool.com/your-answer-a-is-closer-to-what-i-want-but-not-16886602.aspx Subject:  Re: Formula to Calculate Growth Date:  3/13/2002  12:35 AM Author:  ranger54 Number:  33985 of 81362 Your answer (A) is closer to what I want but not quite. Let me give 2 examples: 1st) (easier problem) Suppose that I start an IRA with an initial investment of \$1000 and I want to know how much money I will have in 10 years or 20 years given an expected rate of return. I know the formula to use if I know how long it takes for my money to double:Final value=initial value * 2^(time elapsed/doubling time)--- I think that this is an equivalent formula to yours for (A).2nd) (and the one that I am trying to find a formula for) Suppose that I start an IRA with an initial investment of \$1000 and every year I add \$3000 more to it. What formula can I use to determine how much the IRA will be worth in a certain number of years given an expected rate of return. Also, in this case I would like to use percent expected return per year rather than doubling time. With the formula that you gave (answer A) I could do this by iterative means-calculating how much I earned in interest and adding my new annual investment and starting over with this as my initial value but I would like to avoid the brute force method if possible.Thanks again,Carson Copyright 1996-2016 trademark and the "Fool" logo is a trademark of The Motley Fool, Inc. Contact Us