Sorry if it was started in the wrong section. Please move it if it's the case. I was just looking at the categories in the Main menu bar in the left side not realising there's a programming section. Sorry! I've written a code for a second degree equation solver but I need to add that it should tell me when the values entered are not number and it should then echo a simple "This is not possible" or something, but I've looked around and can't figure out how to do it. Here's the code http://knowledgehunter.org/exercice.txt Here's it in PHP http://knowledgehunter.org/exercice.php Help will be rewarded with thanks and rep =) Thanks a lot!