C# Add Functionallity to BigRational AsDecimal AsScientific

brmsc.cs

        public BigInteger Remainder => Numerator % Denominator;
        private static ulong HashHold;
        private static string DecimalString = "0";
        private static readonly FNV1a64 _Hasher = new FNV1a64();
        public static int DisplayPrecision = 100;
        public string AsDecimal(bool rounding = false, int toDigits = 100)
        {
            var lh = _Hasher.Hash64(Numerator.ToByteArray()) ^ _Hasher.Hash64(Denominator.ToByteArray());
            if (HashHold == lh) return DecimalString;
            if (DisplayPrecision < 0)
            {
                var ret = new StringBuilder();
                ret.Append(Numerator.ToString("R", CultureInfo.InvariantCulture));
                ret.Append(_solidus);
                ret.Append(Denominator.ToString("R", CultureInfo.InvariantCulture));
                DecimalString = ret.ToString();
                HashHold = lh;
                return DecimalString;
            }

            var rv = new StringBuilder(DisplayPrecision + 1);
            rv.Append((Numerator - Remainder) / Denominator + ".");
            var NewNumerator = Remainder * 10;
            for (var i = 0; i < DisplayPrecision; i++)
            {
                rv.Append((NewNumerator - NewNumerator % Denominator) / Denominator);
                NewNumerator = NewNumerator % Denominator * 10;
            }

            DecimalString = rv.ToString();

            if (rounding)
            {
                var dPos = DecimalString.IndexOf(".", StringComparison.Ordinal);
                if (dPos != -1)
                {
                    if (DecimalString.Length + dPos >= toDigits + 1)
                    {
                        var tempStr = new StringBuilder("0.");
                        DecimalString = DecimalString.Substring(dPos + 1, toDigits + 1);
                        var lastDigit = DecimalString.Substring(DecimalString.Length - 1, 1).ToInt32();
                        var nextLastDigit = DecimalString.Substring(DecimalString.Length - 2, 1).ToInt32();
                        tempStr.Append(DecimalString.Substring(0, DecimalString.Length - 2));
                        tempStr.Append(lastDigit >= 5 ? $"{nextLastDigit + 1}" : $"{nextLastDigit}");
                        DecimalString = tempStr.ToString();
                    }
                }

            }

            HashHold = lh;
            return DecimalString;
        }
        public string AsScientific()
        {
            var Offset = 0;
            AsDecimal();
            if (GetWholePart != 0) return DecimalString;
            var dPos = DecimalString.IndexOf(".", StringComparison.Ordinal);
            if (dPos == -1) return DecimalString;
            for (var i = dPos + 1; i < DecimalString.Length; ++i)
                if (DecimalString[i] == '0')
                    Offset++;
                else
                    break;

            if (DecimalString.Length >= Offset + 6)
            {
                var res = new StringBuilder(DecimalString.Substring(Offset + 2, 1));
                res.Append(".");
                res.Append(DecimalString.Substring(Offset + 3));
                res.Append("e-");
                res.Append($"{Offset + 1}");
                return res.ToString();
            }
            else return DecimalString;
        }