There are more stars in the universe than grains of sand on all the beaches on Earth.
Why it is true
The estimated number of stars in the observable universe is about 10 to the power of 24. The number of grains of sand on all the beaches on Earth is estimated at 10 to the power of 21. There are therefore about a thousand times more stars than grains of sand.
Source: ESA
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.