Comments on: What are Significant Figures? http://www.sciencebase.com/science-blog/what-are-significant-figures.html Science Blog from Freelance Science Writer David Bradley Sat, 21 Nov 2009 14:14:50 +0000 http://wordpress.org/?v=2.8.6 hourly 1 By: Harmon http://www.sciencebase.com/science-blog/what-are-significant-figures.html/comment-page-1#comment-63646 Harmon Mon, 12 Feb 2007 14:21:02 +0000 http://www.sciencebase.com/science-blog/what-are-significant-figures.html#comment-63646 When I teach sig figs to my General Chemistry students, I advise them to delay rounding to the correct number of sig figs until the end of the calculation. This helps avoid introducing additional rounding errors. (Of course, carrying all 9 extra non-sig figs is overkill. One extra should do it.) When I teach sig figs to my General Chemistry students, I advise them to delay rounding to the correct number of sig figs until the end of the calculation. This helps avoid introducing additional rounding errors. (Of course, carrying all 9 extra non-sig figs is overkill. One extra should do it.)

]]> By: Lednicer http://www.sciencebase.com/science-blog/what-are-significant-figures.html/comment-page-1#comment-61953 Lednicer Fri, 09 Feb 2007 16:20:14 +0000 http://www.sciencebase.com/science-blog/what-are-significant-figures.html#comment-61953 To add an extra complication most spreadsheet programs such as Lotus and Excel carry out calculations out to 14 (Lotus) or so decimal places no matter what shows on the screen. The Format command only modifies the display NOT the value being used. There is a way to limit the places used in calculations but it is a real pain as there is no global command; it must instead be applied individually to each value every time it appears. This poses a real problem in multistep operations required to calculate analyses that must be submitted to regulatory authorities. Real differences in final numbers can be seen in values calculated by a good hand calculator and those obtained from a spreadsheet. To add an extra complication most spreadsheet programs such as Lotus and Excel carry out calculations out to 14 (Lotus) or so decimal places no matter what shows on the screen. The Format command only modifies the display NOT the value being used. There is a way to limit the places used in calculations but it is a real pain as there is no global command; it must instead be applied individually to each value every time it appears.

This poses a real problem in multistep operations required to calculate analyses that must be submitted to regulatory authorities. Real differences in final numbers can be seen in values calculated by a good hand calculator and those obtained from a spreadsheet.

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