Calculation and the chess master -- The cow in the classroom -- A passion for Pi -- Computing in the surreal realm -- Pythagorus plays ball -- Recycling topology -- Soap films and grid walks -- Mating games and lizards -- Random bits -- Spreading rumors -- Towards a fairer expansion draft -- Cracking the ball-control myth -- Math and a music education -- Sprouts -- Groups, graphs and Paul Erdos -- DNA adds up -- Computing with the EDSAC -- Waring experiments -- Old and new arithmetic -- Matchsticks in the summer.