[I was getting my blood drawn. The technician was quite amused by Allie and started chatting with her. It emerged that I’m 42 years old and she is seven.]
Technician: So… How many times older than you is your mother?
Easy! She’s six times older than me because 42 divided by 7 is six. Which means that she is 35 years older than me – because five groups of 7 is 35. That won’t work next year, but then I can always just subtract – there are always lots of ways to work things out.
Technician: Oh!
I see I also guessed the correct number of vials for your blood, Mum. He DID take three!
Whither Earthlings 