This is fascinating!  Researchers at The University of Auckland anticipate the number  of Earth like planets in the milky way Galaxy to be about 100 billion!  Astronomers think that there are hundreds of billions  of galaxies  in the universe, however the exact number is not known. In  just one image for example, the Hubble Ultra Deep Field, finds there are about  10,000 galaxies visible. The most current estimates guess that there are 100 to 200 billion galaxies in  the Universe, each of which has hundreds of billions of stars. Extrapolating the numbers , the possible # of habitable planets is mind blowing.

http://phys.org/news/2013-04-astronomers-billion-earth-like-planets.html

“Our proposal is to measure the number of Earth-mass planets orbiting stars at distances typically twice the Sun-Earth distance. Our planets will therefore be cooler than the Earth. By interpolating between the Kepler and MOA results, we should get a good estimate of the number of Earth-like, habitable planets in the Galaxy. We anticipate a number in the order of 100 billion.”