[KOOL]

попробуй так:

Код:

uses ..., Math;
...
function GetFloatDigitNum(Eps:extended; MinNum:byte=0):byte;
var ds:byte;
begin
  Result:=MinNum;
  if Eps<1 then
    begin
      ds:=Round(Abs(Math.Log10(eps)));
      if ds>MinNum then
        Result:=ds
    end;
end;