How do I process enormous numbers?

Question

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Most efficient implementation of a large number class

Suppose I needed to calculate 2^150000. Obviously that number is going to exceed the size of an int, float, or double. How can I make a data type that allows normal math functions but exceeds the basic number types?

If this is a "depends which language you use" kind of deal. I will say C#.

Answer 1

See

Most efficient implementation of a large number class

for some leads.