There are more stars in the observable universe than grains of sand on all the beaches on Earth.
Why it is true
Astronomers estimate that there are between 10^22 and 10^24 stars in the universe. Even counting every grain of sand on all the beaches and deserts of our planet, the number of stars is far superior.
Source: NASA
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.