Editing Significant figures (section)

=== Implied uncertainty ===
[[File:Mic speed limit.jpg|thumb|Persnickety sign implies 14.6 is speed violation]]

Uncertainty may be implied by the last significant figure if it is not explicitly expressed.<ref name=":0" /> The implied uncertainty is ± the half of the minimum scale at the last significant figure position. For example, if the mass of an object is reported as 3.78&nbsp;kg without mentioning uncertainty, then ±&nbsp;0.005&nbsp;kg measurement uncertainty may be implied. If the mass of an object is estimated as 3.78 ± 0.07&nbsp;kg, so the actual mass is probably somewhere in the range 3.71 to 3.85&nbsp;kg, and it is desired to report it with a single number, then 3.8&nbsp;kg is the best number to report since its implied uncertainty ±&nbsp;0.05&nbsp;kg gives a mass range of 3.75 to 3.85&nbsp;kg, which is close to the measurement range. If the uncertainty is a bit larger, i.e. 3.78&nbsp;±&nbsp;0.09&nbsp;kg, then 3.8&nbsp;kg is still the best single number to quote, since if "4&nbsp;kg" was reported then a lot of information would be lost.

If there is a need to write the implied uncertainty of a number, then it can be written as <math>x\pm\sigma_{x}</math>with stating it as the implied uncertainty (to prevent readers from recognizing it as the measurement uncertainty), where ''x'' and ''σ<sub>x</sub>'' are the number with an extra zero digit (to follow the rules to write uncertainty above) and the implied uncertainty of it respectively. For example, 6&nbsp;kg with the implied uncertainty ±&nbsp;0.5&nbsp;kg can be stated as 6.0&nbsp;±&nbsp;0.5&nbsp;kg.