1. A man walks into a bar and asks for a drink of water. The bartender gives the man a drink of water, but the man says the water is no good. The bartender thinks for a minute, pulls out a gun and points it at him. The man says, “Thank you,” and walks out.

2. There was once a recluse who never left his home. The only time anyone ever visited him was when his food and supplies were delivered, but they never came inside. Then, one storm winter night when an icy gale was blowing, he had a nervous breakdown. He went upstairs, turned off all the lights and went to bed. Next morning, he had caused the deaths of several hundred people. How?

3. Many shops have prices set just under a round figure, e.g. $9.99 instead of $10.00 or $99.95 instead of $100.00 . It is assumed that this is done because the price seems lower to the consumer. But this is not the reason the practice started. What was the original reason for this pricing method?

4. Why is it better to have round manhole covers than square ones?

5. The famous ‘Penny Black’, the world’s first postage stamp, was introduced in England in 1840. The idea of postage stamps was a great success and was taken up worldwide. Yet the ‘Penny Black’ was in use for only one year before it was replaced by the ‘Penny Red’. Why?

6. Assume there are approximately 5,000,000,000 (5 billion) people on Earth. What would you estimate to be the result, if you multiply together the number of fingers on every person’s left-hands? (For the purposes of this exercise, thumbs count as fingers.) If you cannot estimate the number then try to guess how long the number would be.

7. An American nightclub called ‘The Coconut Grove’ had a terrible fire in which over 400 people died. A simple design flaw in the building led to the death toll being so high. Subsequently, regulations were changed to ensure that all public buildings throughout the country eliminated this one detail which proved so deadly. What was it?