BigInteger bi=Bigger.Parse("999999999999999999999999999999999999999999999999999999999999999999999999999999");
Console.WriteLine(bi);
Console.WriteLine(bi.IsEven);
Console.WriteLine(bi.IsOne);
BigInteger big=BigInteger.Multiply(bi,BigInteger.Parse("999999999999999999999999999999999999999999999999999999"));
Console.WriteLine(big);
原文：http://www.cnblogs.com/Fred1987/p/5557749.html