How many elliptical galaxies are there in the universe?
20 billion is a good guess.
There are 100,000,000,000 galaxies in the universe (best guess). 20 percent of known galaxies are elliptical. If the known galaxies are a good representation of the universe make up then that would mean that 20 percent of all the galaxies would be elliptical.
Since the total number of galaxies is only a good guess and saying 20 percent of galaxies are elliptical is an assumption, the accuracy of the above answer is questionable.