Extrapolating from this Hubble image, scientists have estimated that the universe contains at least 200 BILLION GALAXIES, EACH HAVING an average of 100 BILLION STARS!!!!!!!
Also, our sun is an average sized star.
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According to the Space Telescope Science Institute, the Hubble Ultra Deep Field has an angular size of 11.5 square arcminutes. That means that it would take 12,913,983 Deep Field images to cover the entire sphere of the sky!

Just for fun, let’s calculate roughly how many stars that implies in the observable universe: The ultra deep field image has about 10,000 galaxies in it. If we assume that each galaxy has 100,000,000,000 (100 billion) stars, then the approximate number of stars in the visible universe is absolutely staggering: 123,000,000,000,000,000,000

123 quintillion stars! That’s 123 billion billion. 123 million million million. (source)