compoundInterest.html

<html>

<head>
    <script type="text/JavaScript">
        function get(eid) {return document.getElementById(eid);};
        function calculate() {
            var P = parseFloat(get('P').value);
            var r = parseFloat(get('r').value);
            var n = parseFloat(get('n').value);
            var t = parseFloat(get('t').value);
            if (isNaN(P) || isNaN(r) || isNaN(n) || isNaN(t)) {
                alert('all inputs must be numbers');
                return;
            }
            var A = P*Math.pow((1 + r/n), n*t);
            get('A').innerHTML = A;
        };
    </script>
</head>

<body>
    <pre>
    Calculate the accumulated value of principal on deposit as:

    A = P(1 + r/n)^nt

    where:

        A = amount of money accumulated after n years, including interest

        P = principal amount (the initial amount you borrow or deposit)
        r = annual rate of interest (as a decimal)
        n = number of times the interest is compounded per year
        t = number of years the amount is deposited
    </pre>
    <form>
        <p>
            <input id="P" type="text" /> = P
                (principal)<br />
            <input id="r" type="text" /> = r
                (rate of interest - decimal)<br />
            <input id="n" type="text" /> = n
                (number of times interest is compounded per year)<br />
            <input id="t" type="text" /> = t
                (number of years principal is deposited)<br />
            <input type="button" value="calculate" onclick="calculate()" /><br /><br />
            Accumulated Amount - A = <span id="A"></span>
        <p>
    </form>
</body>

</html>