A Disappearing Number is a 2007 play co-written and devised by the Théâtre de Complicité company and directed and conceived by English playwright Simon McBurney.

A Disappearing Number premiered in Plymouth in March 2007,[1] toured internationally, and played at The Barbican Centre in Autumn 2007 and 2008[2] and at Lincoln Center in July 2010.

The cast in order of appearance: Firdous Bamji, Saskia Reeves, David Annen, Paul Bhattacharjee, Shane Shambu, Divya Kasturi and Chetna Pandya.

It interweaves the passionate intellectual relationship between Hardy and the more intuitive Ramanujan, with the present-day story of Ruth, an English maths lecturer, and her husband, Al Cooper, a globe-trotting Indian-American businessman "to illuminate the beauty and the patterns – the mystery – of mathematics.

Meanwhile, 100 years previously, Ramanujan is travelling in the opposite direction, making the trip to England, where he works with Hardy on maths and contracts tuberculosis.

Partition (as a maths concept) is explored, and diverging and converging series in mathematics become a metaphor for the Indian diaspora.