Numbers to Blow Your Mind

Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space. ~ Hitchhiker's Guide to the Galaxy

Seven Octillion (7x10²⁷)
This is the number of atoms in the human body.

A Googol (10¹⁰⁰)

A Googol is ten to the power of 100, one followed by 100 zeros. For perspective, there are about 10⁸⁰ atoms in the entire universe. So a Googol would be the number of atoms in one hundred quintillion universes.

8604 Years
Tony Padilla is Lecturer in Physics at the University of Nottingham in England. As an exercise for Numberphile, he calculated the number of years it would take for humans to consume every available atom in the universe. At our present rate of population growth, by the year 10621, there would be no atoms left to make stars or bunnies as every atom in the entire universe will be dedicated to the two sexdecillion humans squeezed into the cosmos. Birth control, maybe?

When you are put into the Vortex you are given just one momentary glimpse of the entire unimaginable infinity of creation, and somewhere in it there's a tiny little speck, a microscopic dot on a microscopic dot, which says, "You are here." ~ Hitchhiker's Guide to the Galaxy

Graham's Number
This number makes a Googol look like a speck of dust on a universe of universes. Graham's number describes connectivity in multidimensional hypercubes and if you want to know more get a doctorate in mathematics. It is impossible to imagine the size of this number.

If you wrote googol digits on an atom and filled the universe with a googol of such inscribed atoms and did it again with a googol number of universes you still wouldn't be close to writing down the full length of the number. Yet it is a real number and they know that the final digit of the number is a 7.