Be careful when doing any kind of calculations with numbers that have been passed through PHP's number_format function as they can lead to unexpected results. The problems lie with the thousands separator (or the decimal separator if you use anything other than '.'). Here's an example:
[email protected]:/$ php -a Interactive shell php > $number = 1234.56; php > echo $number; 1234.56 php > $number = number_format($number, 2); php > echo $number; 1,234.56 php > echo $number * 100; 100 php >
The issue is that the calculation ignores everything after the thousands separator ' , '.