Math::BigInt::Calc inherits from Math::BigInt::Lib.
In this library, the numbers are represented in base B = 10**N, where N is the
largest possible value that does not cause overflow in the intermediate
computations. The base B elements are stored in an array, with the least
significant element stored in array element zero. There are no leading zero
elements, except a single zero element when the number is zero.
For instance, if B = 10000, the number 1234567890 is represented internally
as [7890, 3456, 12].