[Miffymycat]

Let’s say I have a class A 25ml pipet with an uncertainty of +/- 0.24ml.
 
If I want to express the volume of the pipet to the correct number of sig figs to say determine the sig figs in a final answer- what is it?
 
Is it 25 ie two, because that is the marking?
 
Or 25.00 ie four, because the uncertainty limits the range to 24.76 – 25.24, which are 4 sig fig values?
 
Or 25.0 ie three, the third being 0.24 rounded down to 1 sig fig ie 0?

[Dan]

You can only quote to 3sf (25.0) if the volume lies in the range 24.95-25.05, because anything outside this range does not round to 25.0.

You can quote to 2sf if the volume lies in the 24.5-25.5 range, because anything in this range rounds to 25.

[Miffymycat]

Thank you - thats nice and simple.
If the volume in this example was 24.05 or 25.05, (ie 25 +/- .05) how to proceed?  Is there a convention for rounding up or down?