Imagine the smallest sensible length in the universe???—???that is, the smallest length for which the notion of distance makes sense, a little like pixels in a digital image. This is called a Planck length. In order to grasp just how small this distance really is, a Planck volume, which is Planck length cubed, is so small that there are more Planck volumes inside a cubic meter than there are cubic meters in the known universe.
A Planck length is roughly the size you get if you divide the diameter of a proton by a hundred billion billion! It is unimaginable tiny and no one really understands how nature works at this scale.
Now imagine that you can write numbers in Planck-length font. To put it in a scientific context, if you write down a number with an Avogadro’s number of digits using this font, it would fill up a hundredth of the diameter of an atom.