Can you guess?
Say what you think first. Then watch what really happens. Nothing here is scored.
- The birthday roomPeople walk into a room one at a time. A year has 365 days.Open →
- The Shah's chessboardThe man who invented chess asked for wheat instead of gold. The Shah laughed and said yes.Open →
- When was the jar half full?One bacterium in a jar at 11:00. It splits in two every minute. At 12:00 the jar is full.Open →
- The lily pondA water lily patch doubles in size every day. On day 30 it covers the whole pond.Open →
- Folding paper to the MoonA sheet of paper is a tenth of a millimetre thick. Fold it in half and it doubles.Open →
- One coin, or a thousand a day?Offer A: 1000 coins every day for 30 days. Offer B: 1 coin today, 2 tomorrow, 4 the day after — doubling every day for 30 days.Open →