Ferryman: "Mommy, I can't sleep!"
Ferryman's mother: "Aww Well, try counting ferries. How many ferries arrived at Dover today, my dear?"
Ferryman: "13:00 - 4 ferries left Dover, 3 arrived at Dover. 13:10 - 2 ferries left Dover, 1 arrived at Dover. 13:20 - 3 ferries left Dover, 2 arrived at Dover. 13:30 - 2 ferries left Dover, 2 arrived at Dover....
13:40 - 4 ferries left Dover...
10000000 arrived at Dover... Woah!
Mommy, I have a nightmare again!"