From what I've read, there are more stars than grains of sand on all of Earths beaches.
3 or 4
None ... They're all in space
The figure is beyond comprehension.
According to the UCSB Science Line the number is 1 billion trillion and that's a lot of cheese. God must have worked pretty hard during those 6 days and 6 nights. It's no wonder he took some personal time on Saturday.
Minimum = 19,000,000
Maximum = 2,147,483,647
The estimate is 100,000,000,000,000,000,000,000,000,000 stars, but as we find more galaxies the number might be even larger then that.
Depending where you are, there are over 6000 stars visible at night with the naked eye. None are actually "in the sky".
Beyond that, there are countless billions of stars contained within each of the billions of galaxies in what's called the "observable universe".