How many galaxies are in the universe?
We can only answer regarding the known universe.
Since there is an estimated number of atoms in the known universe, there has to be an estimated number of galaxies. The estimate is somewhere between 100-200 billion galaxies.
Incidentally the reason the number of atoms was estimated was due to the Shannon Number, which was the estimated number of possible chess games you can play based on an average game length of 40 pairs of moves. The Shannon number is usually estimated to be in the realm of