Remember when we all thought there were only 9 (OK, 8) planets?

There are now known to be:

• 948 confirmed planets around 697 Stars
• 141 Systems with Multiple Planets
• 3,588 Kepler Candidates and Confirmed Planets

Extrapolating from the above, there are something like a hundred billion planets in our galaxy alone; which is one of untold billions of galaxies.

For the breakdowns, see this NASA page, plus this update, and this article: http://news.nationalgeographic.com/news/billions-of-earthlike-planets-found-in-milky-way/