Let's see if I get you right.

You would like to invest startAmount at a rate of interestRate and you'd like to know how much money you'll have at the end of n investment periods.

In this case, you'd have the following formula: totalMoney = startAmount * (1 + interestRate)^{n}

, where interestRate is expressed as a floating-point number (e.g. 10% --> 0.10)

Now, you ask how you can do this without raising anything to a certain power.

Well, if you take the basic definition of the a^{b}, it means that you multiply a with itself b times.

In programming terms, instead of using the pow() function, you can write a loop that multiplies a given number of times. E.g.:

floatCalculateInterest(floatstartAmount,floatinterestRate,size_tn) {floatmultiplier = 1.0 + interestRate;for(size_ti = 0; i < n; i++) startAmount *= multiplier;returnstartAmount; }

Is this what you're after?