Those of you living on one level may take this opportunity to put the kettle on :-)
Do you know, without going to check, how many stairs there are between upstairs and downstairs? No, I don't want to know - I just want to know whether you know.
No real reason, really. It just came up in conversation. My wife does not know how many stairs in this house. She thinks knowing is seriously weird. My son doesn't know. My brother doesn't know how many stairs in his house. I know, of course. I have always known exactly how many stairs there are in every house in which I've lived, which, according to Wifey, makes me seriously weird.