Not well! But that's in no way relevant to the point, which is that we are demonstrably capable of creating machines that can perform tasks of intelligence that we cannot.
Sure, though that really began with the abacus. A skilled abacus user can perform calculations faster than most people can with a calculator. They practice until it's all muscle memory. I think this demonstrates that there's actually very little intelligence involved in arithmetic.
Sure, but how would the average guy fare at the same task?