Numbers are tough to learn as a child.  One, two – many.  That is how you first see the world, and as how lots of other mammals and birds see the world.  Then you learn the numbers and the idea of counting, then connecting the idea that you can count a large number of individual things which makes the number of things.  It might seem that we understand numbers as adults, but unfortunately we cannot easily deal with large numbers. Remember poor Carl Sagan with his “Billions and Billions” of stars, atoms, lightyears or whatever else he was talking about. – We had no clue how many suns, galaxies, base pairs, cells or light years he meant, just that it was a lot.