The Sand Reckoner, addressed to
Gelon, King of Syracuse, he attempted to count the number of grains of
sand required to fill the entire universe. Assuming that one poppy-head
would not contain more than 10,000 grains of sand, and that its diameter
is not less than
This is a unique and extraordinary achievement for Archimedes' time. The ancient Greeks had little interest in numbers outside of geometry.
Nowadays, the total number of particles in the universe has been variously estimated at numbers from 1072 up to 1087. The total number of atoms in your body is about 1028. If the universe were packed solid with neutrons, there would still be only 10128 particles, a number larger than a googol but much smaller than a googolplex.
You don't need huge volumes of particles to get a glimpse of large numbers, however. All you need is combinatorics. How many ways are there to arrange 30 books on a bookshelf? The answer is 30 factorial (which is abbreviated 30!), or 265,252,859,812,191,058,636,308,480,000,000.
Mathematicians often have to use really big numbers in their work. There is much interest in finding huge numbers with certain properties. Examples are odd perfect numbers (none of which has yet been found) and Mersenne primes,
If you're interested in getting a further perspective on the size of the universe, see Universe facts on our sister site, All Fun and Games. You may also find more facts about large numbers there.