Sometimes, Mac OS X 10.3 Panther Calculator results may include "rounding errors". Choose a lower Precision setting from the View menu to avoid this issue in the main Calculator window.
Note: This document applies to Mac OS X 10.3 through 10.3.9.
Sometimes you may see different results in the Paper Tape window. For example, if you calculate 77 + .1, the result is 77.1 in the Calculator window as expected; but the Paper Tape window displays a result of "77.09999999999999".
Since Calculator uses floating-point arithmetic, the calculation is the expected result. Choose a lower Precision setting from the View menu to avoid this issue in the main Calculator window.
Additional information
For an advanced discussion of why this happens, see "What Every Computer Scientist Should Know About Floating-Point Arithmetic" (http://docs.sun.com/source/806-3568/ncg_goldberg.html).
Important: Mention of third-party websites and products is for informational purposes only and constitutes neither an endorsement nor a recommendation. Apple assumes no responsibility with regard to the selection, performance or use of information or products found at third-party websites. Apple provides this only as a convenience to our users. Apple has not tested the information found on these sites and makes no representations regarding its accuracy or reliability. There are risks inherent in the use of any information or products found on the Internet, and Apple assumes no responsibility in this regard. Please understand that a third-party site is independent from Apple and that Apple has no control over the content on that website.