Sig Figs Revisited

[Strassia]

A few points: Sig figs are not the same as errors. The are more a matter of accuracy. The reason you keep track of significant figures is because once you go below them the numbers become meaningless. If I multiply 2.13 * 5.14444 it is normally assumed that both of those numbers are rounded, not exact. In that case there is no information value to anything beyond 11.0 because we do not know what the digits beyond that really are. Second, you can have numbers with infinite significant figures. For example, if you are calculating the volume of the telephone pole and you measure the diameter, the volume would be (d/2)^2pilength. The 2 is an integer factor that has basically infinite significant figures.

Jonathan.

[CookingWithGas]

@Strassia

A few points: Sig figs are not the same as errors. The are more a matter of accuracy.

Actually they do indicate error. Not error in the sense of “somebody goofed” but in “the error inherent in the measurement due to the amount of available precision.” If my ruler is marked off in tenths of an inch, and I tell you that I measured something at 5.2 inches, you know that the object may really have been anywhere from 5.150-5.249 to produce that measurement. So the error is about ±0.05.

Also, significant digits are a matter of precision, not accuracy. My stopwatch measures to the tenth of a second (precision), but it measures 1 second slow for each minute (accuracy).