From guessing the weight of a cow or the number of sweets in a jar, there is evidence that the average of a crowd's guesses can deliver surprisingly accurate results. Professor Marcus du Sautoy carries out a number of live interactive quizzes and experiments to test these ideas and look at how these principals can be harnessed for citizen science projects. This event was hosted in partnership with the University of Oxford as part of the AHRC's Constructing Scientific Communities project. For our full events schedule, see - ow.ly/CRdT30icVtq