The Great Math Mystery: What on Earth is $0^0$?

Mathematics is usually full of clear rules. Two plus two is four. A triangle’s angles add up to $180^circ$. But every once in a while, math presents us with a puzzle so fascinating and controversial that even the greatest geniuses in history couldn’t agree on the answer.

One of the most famous puzzles in all of arithmetic is this: What is $0^0$ (zero to the power of zero)?