The Highest Number

What is the highest number there is? Let's try and find out by working our way up. To save myself from having to write down a lot of digits, let me first explain the scientific notation:

• 1 × 10² = 1 × 10 × 10 = 100
• 1 × 10³ = 1 × 10 × 10 × 10 = 1000
• 1 × 10⁴ = 1 × 10 × 10 × 10 × 10 = 10000

Basically, powers of 10 can be used to define the number of zeros that follow the ‘1’. So here's some large numbers you might know: a million, a billion, a trillion, a quadrillion... These can be written respectively as 10⁶, 10⁹, 10¹² and 10¹⁵. You might knew these first few, but that list actually goes on for a while. Take for example a vigintillion, which is 10⁶³. Are there any higher?

Of course! How about the googol? It is notated as 10¹⁰⁰. That's a ‘1’ with a hundred zeros! Is this the largest number? Nah, we can put at least the centillion (10³⁰³), septuagintacentillion (10⁵¹³) and the millinillion (10³⁰⁰³) on the table.

We need to do better than this, so let's push it into crazy territory. A googolplex is 10^googol — yes, that's 10 to the power of a googol. A ‘1’ with a googol zeros. 10¹⁰¹⁰⁰. Fine! It is a 1 with 10 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 000 zeros. So as you can see I just wrote out a googol. I cannot write out a googolplex: there is not enough room in our universe to do so. See, the number of atoms in the observable universe is estimated to be around 10⁸⁰. This means that writing down a googolplex requires far more zeros than there are atoms in the universe!