The human body is made up of about 7 octillion atoms.
Why it is true
This incredibly massive number (7 followed by 27 zeros) highlights the sheer microscopic complexity and scale of matter that forms a single human being.
Source: Physics
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.