public string ToDisplayString()
        {
            var str = "";

            if (Operator != null)
            {
                str = Operator.ToDisplayString();
            }
            if (RhsNumber != null)
            {
                str = str + " " + RhsNumber.ToDisplayString();
            }

            return(str);
        }
        public decimal Execute()
        {
            RhsNumber.Lock();

            return(Operator.Execute(LhsNumber.ToDecimal(), RhsNumber.ToDecimal()));
        }