1 If your precocious nine-year old daughter asked you to place one penny on the first square of a chessboard, two pence on the second square, four pence on the third, and so on, you would need to put £92 million billion on the 64th and final square. 2 Prime numbers (2, 3, 5, 7, 13 and so on ...) are divisible only by themselves and the number one. The largest prime number yet discovered has 2,098,960 digits. If we were to print nothing except this number across all sections of today's and next week's Observers (containing around 250,000...