https://www.sciencenews.org/article/mathematicians-may-have-found-fastest-way-multiply-huge-numbers
In the new study, the researchers considered only numbers with more than roughly 10^^214857091104455251940635045059417341952 digits when written in binary, in which numbers are encoded with a sequence of 0s and 1s. But the scientists didn’t actually perform any of these massive multiplications, because that’s vastly more digits than the number of atoms in the universe.