theshoeshiner opened a new pull request, #1095:
URL: https://github.com/apache/commons-lang/pull/1095

   A util method in NumberUtils that counts the number of significant figures 
in a decimal strings of standard / exponential format. e.g.(101, 102.1, 5.1e2, 
1.001, 0.2e4, etc...)
   
   This method counts the number of "significant figures" according to standard 
mathematical rules (details and references are in the javadoc). It must operate 
on a string because the rules themselves inherently depend on the string 
representation and not the underlying numeric value. The rules are well 
documented and widely accepted, aside from zero values, which are not usually 
covered by the conventions and the choice as to how to interpret is documented 
in the javadoc.
   
   My first instinct was that this belonged in commons-math or commons-numbers, 
as the concept of significant figures is usually necessary in scientific / 
mathematical fields, but thus far it doesnt seem to be a good fit. Decided Id 
create the PR here so that at least the implementation is out there for review 
and perhaps this discussion will find it a better home. I do feel like this is 
a valuable feature because any manipulation of numerical scientific data that 
needs to be accurate (e.g. clinical data) ultimately needs to respect 
significant figure counts.
   
   There are 7 basic rules that the method follows, #1-5 being the core sigfig 
rules that you'll find on most external sources, #6 to explain how zero values 
are handled, and #7 to explain how exponents are handled (or excluded, rather). 
The overall format of the string is validated, with IAEs thrown for invalid 
characters or formatting.
   


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