Can you create recursion within a single cell in Excel?

I don't know how you can do recursion within a particular cell in Excel. However, there is a formula that you can use to calculate compound interest:

=PV * (1 + R)^N

Where PV is the beginning (present) value on which the interest will be paid, R is the interest rate per period (as a decimal, like 0.02 for 2%), and N is the number of periods. So if you have the beginning value in cell A1, the interest rate in cell B1, and the number of periods in cell C1, your formula would be:

=A1 * (1 + B1)^C1

If you only want to see the actual interest earned (not the total ending value at the end of the timeframe), you would then subtract the PV:

=(A1 * (1 + B1)^C1) - A1

I hope that helps!

never heard of recursion within a single cell

most likely need to use Visual Basic