Implicitly cast a BigInteger to a standard numeric type and explicitly cast in the other direction.
For instance:
using System;
using System.Numerics;
class Sample
{
public static void Main()
{
double g1 = 1e100; // implicit cast
BigInteger g2 = (BigInteger)g1; // explicit cast
Console.WriteLine(g2);
}
}
The output:
10000000000000000159028911097599180468360808563945281389781327557747838772170381060813469985856815104