First, computers don't really care about large numbers. For us doing maths on small numbers is easier while computing big numbers requires keeping some stuff in your head or writing it down, which slows the whole process. For computers it's equally easy as long as the number fits into a specific portion of memory i.e. does not exceed some very large number.

Second, modern software is very advanced. Back in the day we had much weaker computers, so we had to do all sorts of math tricks to get a solution that is both fast and precise. Nowdays the pressure to come up with new cool math is not as high, but known stuff still gets used to make computations faster.