Where are all the US Paralympics gold medals?
Why did the USA top the gold medals league in the Olympics, but not the Paralympics?
Ruth Alexander examines the performance numbers of the London 2012 Paralympic Games, and discovers which countries are punching above their weight, and which below.
Plus, how many songs could ever be written?
Mathematically-minded evolutionary biologist Yan Wong answers this listener's question: "I'm always amazed by the number of songs one can recognise on hearing the first second or two of music. Is it possible to calculate the total number of potential opening bars? Surely it must be finite?"
(Image: (L-R) Arnu Fourie of South Africa, Jonnie Peacock of Great Britain, Richard Browne of the United States, Oscar Pistorius of South Africa, and Alan Fonteles Cardoso Oliveira of Brazil, compete in the T44 100m at the London 2012 Paralympic Games. Photo by Jamie McDonald/Getty Images)