This is a well-known problem: round-off error. Not a bug, because the calculator isn't powerful enough to work with exact figures. ----------- STL137@aol.com ===> Website: http://137.tsx.org <=== Find my PGP Key Fingerprint there. Quotes: http://quote.cjb.net "The simplest schoolboy is now familiar with truths for which Archimedes would have sacrificed his life" - Ernest Renan