Never underestimate the power of CPAN:

  Math::SigFigs - do math with correct handling of significant figures

  In many scientific applications, it is often useful to be
  able to format numbers with a given number of significant
  figures, or to do math in such a way as to maintain the
  correct number of significant figures.  The rules for
  significant figures are too complicated to be handled
  solely using the sprintf function (unless you happen to be
  Randal Schwartz :-).

In reply to Re: significant digits in computations by Perlmage
in thread significant digits in computations by daemonchild

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