One of the messages was from another mate, Dave, who had enclosed a little maths problem that had been passed on to him by someone else who seems to have received it as a regular brain teaser post from some site or other.
I note it here simply because it took me a lot longer to do than I'd have thought, and because I'm sure there's an easier approach than I used. Mind you, given the number of beers I drank this evening, I'm amazed I could work it out at all :-).
Perhaps it would have been easier if I'd changed the ingredients from coffee and milk to gin and tonic!
There are two cups on a table; one containing 10mL of black coffee and one containing 10mL of milk.
Take 1mL from the cup of milk and pour it into the cup of coffee.
Then take 1mL from the new mix and pour it into the cup containing only milk.
Is there more milk in the cup of coffee or more coffee in the cup of milk?