If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

If eleven plus two equals one, what does nine plus five equal?

Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

A chess tournament is taking place on knock-out terms (the one who loses the match is out of the game).
(a) If 10 matches are played in total, how many players participated?
(b) If 20 players took part in the tournament, how many matches were played?

What is the centre of gravity?

What is the largest number you can write with just 3 digits?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

I taste better than I can smell. Who am I?

A woman lives in a skyscraper thirty-six floors high and is served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up than down. Why?

Can you find out the remainder when 3^300 is divided by 5?