Thank you! Thank You! Thank You! tye I could not have said it better myself. The focus of my post was not the fact that I didn't understand the output of printf necessarily but why would 4083 - 4083.0 = "-9.09494701772928e-13! My perl script was written in the same context as your script. For a quick and dirty report to show my users the analysis of an issue. Thank you all for your explanations. They were all good. I'll just mask everything with an int(). j