There are more ways to shuffle a 52-card deck than there are atoms on Earth.
Why it is true
The number of possible combinations of a 52-card deck is 52 factorial, a number with 68 digits. It is much larger than the estimated number of atoms on Earth, about 10 to the power of 50. That is why every well-shuffled deck is probably unique in history.
Source: Mathematical Association
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.