There's a kind of nausea or vertigo I get when confronted by an extremely large number. Kant called it the mathematical sublime, the terror before something that is "large beyond all comparison". At a certain point numbers start expanding out beyond any ordinary experience of the world. I can eat three apples; three million apples is just an abstract enormity. It makes no sense. Kant's example was the "kind of perplexity that is said to seize the spectator who for the first time enters St. Peter's Basilica in Rome". It's just too big to fit inside the puny human skull; you can't comprehend the size of the thing without running up against some kind of unthinking awe.