I agree that it’s better to state the uncertainty [1] together with the measurement, but when this isn’t done, there is a standard convention for significant di

I agree that it’s better to state the uncertainty [1] together with the measurement, but when this isn’t done, there is a standard convention for significant digits, explained in ISO 80000-1:2009 [2], subclause 7.3.4: When a number is given without any further information, it is generally interpreted so that the last digit is rounded with a rounding range equal to 1 in the last digit (see Annex B). Thus, for example, the number 401 008 is generally assumed to represent a value between 401 007,5 and 401 008,5. In this case, the maximum magnitude of the error in the number 401 008 is 0,5. This is consistent with the author’s “less than half a unit.” [1] JCGM 100:2008, Evaluation of measurement data — Guide to the expression of uncertainty in measurement, https://www.iso.org/sites/JCGM/GUM-JCGM100.htm https://www.iso.org/sites/JCGM/GUM-JCGM100.htm [2] ISO 80000-1:2009, Quantities and units — Part 1: General