Another View of Significant Figures Several recent issues of THIS JOIIRNAI. have carried preseriptirms for handling the issue of significant figures. There is usually little trouble with determining the number of significant figures in a measurement, except in the case where zeros follow the last nonzero digit. A number like 120 is usually treated as though there were two significant figures, unless something else leads you to helieve the zero issignificant. The ambiguity surmunding the treatment of the trailingzen, can he overcome by requiring that trailingzeros he written only if they are meant to he significant. For example, the number 600 would have three sienificant fieures. If 500 were exoressed with onlv one sienificant fieure. it would he written as 5 X 10'.
1) Leading zeros in a numher are not significant. Leading zeros are those coming before the first nonzero dlgit. 2) Trailing zeros in a number are significant. Trailing zeros are those coming after the last nonzero digit in a number. 3) All other digits in the number are significant. Since introducing this method in my classes, I have noticed a significant reduction in the confusion and error assoeiated with significant figures.
Chares R. Ward University of North Carolina at Wilmington Wilmington. NC 28401
616
Journal of Chemical Education
