30 ) {
$error_message = 'Years must be less than 31.';
// set error message to empty string if no invalid entries
} else {
$error_message = '';
}
// if an error message exists, go to the index page
if ($error_message != '') {
include('index.php');
exit();
}
// calculate the future value
$future_value = $investment;
for ($i = 1; $i <= $years; $i++) {
$future_value += $future_value * $interest_rate * .01;
}
// apply currency and percent formatting
$investment_f = '$'.number_format($investment, 2);
$yearly_rate_f = $interest_rate.'%';
$future_value_f = '$'.number_format($future_value, 2);
?>
Future Value Calculator