function calculate(amount, initial, rate, years) 
{
	amount = amount.replace(/[^0-9]+/g, '');

    var p = rate / (12 * 100);
    return Math.round((amount - initial) * (p + p / (Math.pow(1 + p, years * 12) - 1)));
}

function formatNumber(nStr) 
{
    nStr += '';
    x = nStr.split('.');
    x1 = x[0];
    x2 = x.length > 1 ? '.' + x[1] : '';

    var rgx = /(\d+)(\d{3})/;

    while (rgx.test(x1)) 
        x1 = x1.replace(rgx, '$1' + ' ' + '$2'); 
    
    return x1 + x2;
   }