Compound Interest

The goal here is to teach you how to turn a complex equation into a single line of code:

This is the equation for compound interest: A = P(1 + r/n)^nt

Where A is the final amount after t years, r is the annual nominal interest rate, n is the number of times the interest is compounded per year, and P is the initial amount of money.

Write a function which takes P,r,n, and t, returns the A value, but only contains a single line of code (braces and comments don’t count). If you aren't comfortable with functions or methods, assume you have those 4 variables and write one line of code to declare a variable called A, and assign it the right answer.

If you have trouble with this question, try practising expression creation on our Code Calculator (C# only, though some Java will work because of syntax similarities).

Try not to look at the answers until you’ve solved the problem

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C#:

Show Code >>

public static double compoundCalculator(double principleAmount, double rate, int compoundsPerYer, double years)
{
    return principleAmount*Math.Pow((1+rate/compoundsPerYer),compoundsPerYer*years);
}

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Java:

Show Code >>

public static double compoundCalculator(double principleAmount, double rate, int compoundsPerYer, double years)
{
    return principleAmount*Math.pow((1+rate/compoundsPerYer),compoundsPerYer*years);
}

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Python:

Show Code >>

def compoundCalculator(principleAmount, rate, compoundsPerYer, years):
    return principleAmount*pow((1+rate/compoundsPerYer),compoundsPerYer*years)

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Updated 25 November 2014 by Matthew F.