code: function Fe(pt,ut,bt){// Remove trailing zeros.
  for(var ht=1,mt=ut.length;!ut[--mt];ut.pop());// Calculate the base 10 exponent. First get the number of digits of c[0].
  for(mt=ut[0];10<=mt;mt/=10,ht++);// Overflow?
  return(bt=ht+bt*Re-1)>$e?pt.c=pt.e=null:bt<Qe?pt.c=[pt.e=0]:(pt.e=bt,pt.c=ut),pt}
docs: /*
  Strip trailing zeros, calculate base 10 exponent and check against MIN_EXP and MAX_EXP.
  Called by minus, plus and times.