A friend of mine emptied a box of matches on the table and divided them into three heaps, while we stood around him wondering what he was going to do next.

He looked up and said, “Well friends, we have here three uneven heaps. Of course you know that a match box contains altogether 48 matches. This I don’t have to tell you. And I am not going to tell you how many there are in each heap.”

“What do you want us to do?” one of the men shouted.

“Look well, and think. If I take off as many matches from the first heap as there are in the second and add them to the second, and then take as many from the second as there are in the third and add them to the third, and lastly if I take as many from the third as there are in the first and add them to the firstâ€”then the heaps will all have equal number of matches.”

As we all stood there puzzled he asked, “Can you tell me how many were there originally in each heap?” Can you?

You have two hourglasses, a 7 minute one and an 11 minute one. Using just these two hourglasses, how can you accurately time 15 minutes?

If one and a half teenagers can eat one and a half pizzas in one and a half days, how many pizzas can 9 teenagers eat in 3 days?