Famed for his popular science programmes for children in the 1970s and 1980s, including Think of a Number, and his appearances on Playschool, Johnny Ball is now a judge on the panel for the Aventis prize for science books.

He has agreed to answer 10 questions from Guardian Unlimited readers on the day of the award ceremony - May 16 - and we have 10 signed copies of his new mathematics book for children, Think of a Number (Dorling Kindersley), to give away for the 10 best questions.

Email your questions to books.editor@guardianunlimited.co.uk by midnight on Sunday May 14 for the chance to win a copy of the book and have your question answered by Johnny Ball.