BigDecimal is an arbitrary precision floating point number class.
Like other floating point number implementations, it stores a Mantissa and an Exponent. The difference is, these values are of type BigInteger, and so can be arbitrary precision.
If you just want the compiled binaries, just include it in your project as a nuget package, or extract the assembly from the nuget package (a .nupkg file is just a .zip file renamed): https://www.nuget.org/packages/ExtendedNumerics.BigDecimal
Example usage:
Console.WriteLine(BigDecimal.Precision);
// 5000
BigDecimal.Precision = 200; // Tone down the precision for this demo.
Console.WriteLine(BigDecimal.Precision);
// 200
BigDecimal goldenRatio = BigDecimal.Divide(BigDecimal.Add(BigDecimal.One, BigDecimal.Pow(5d, 0.5d)), BigDecimal.Parse("2"));
BigDecimal almostInteger = BigDecimal.Pow(goldenRatio, 23);
Console.WriteLine(almostInteger);
// 64079.000015605783843835009599722600391518338454771405992063505171997949372951472701529422358634915404757740005027416333594519349348824890921372720968246769717009339797514969003242216358994087504831741
Console.WriteLine(almostInteger.Mantissa);
// 64079000015605783843835009599722600391518338454771405992063505171997949372951472701529422358634915404757740005027416333594519349348824890921372720968246769717009339797514969003242216358994087504831741
Console.WriteLine(almostInteger.Exponent);
// -193
BigDecimal X = BigDecimal.Parse("0.000551876379690949227373068432671081677704194260485651214128035320088300220750");
Console.WriteLine(X);
// 0.00055187637969094922737306843267108167770419426048565121412803532008830022075
BigDecimal result = BigDecimal.Divide(BigDecimal.One, X);
Console.WriteLine(result);
// 1812.000000000000000000000000000000000000000000000000000000000000000000000001