IsNumber

     public   bool  IsNumber(String strNumber)
         ... {
            Regex objNotNumberPattern=new Regex("[^0-9.-]");
            Regex objTwoDotPattern=new Regex("[0-9]*[.][0-9]*[.][0-9]*");
            Regex objTwoMinusPattern=new Regex("[0-9]*[-][0-9]*[-][0-9]*");
            String strValidRealPattern="^([-]|[.]|[-.]|[0-9])[0-9]*[.]*[0-9]+$";
            String strValidIntegerPattern="^([-]|[0-9])[0-9]*$";
            Regex objNumberPattern =new Regex("(" + strValidRealPattern +")|(" + strValidIntegerPattern + ")");

            return !objNotNumberPattern.IsMatch(strNumber) &&
                !objTwoDotPattern.IsMatch(strNumber) &&
                !objTwoMinusPattern.IsMatch(strNumber) &&
                objNumberPattern.IsMatch(strNumber);
        }