Talk:Whole number rule

Meaning of accuracy > 99%?
What exactly is meant by an accuracy better than 99%? What quantity is greater than 99% (or less than 1%) of what other quantity?

I think that a much clearer statement is found in the article Mass number, which says that the isotopic mass is usually within 0.1 u of the mass number. Dirac66 (talk) 23:24, 13 August 2012 (UTC)