Prime Number Champ
Updated at 10:11 pm on 24 February 2014
Originally aired on Nights, Monday 24 February 2014
How a fascination for Prime numbers - natural numbers greater than one that have no positive divisors other than one and itself - led to the discovery of what is still currently the largest known of one of these.
With Dr Curtis Cooper of the maths and computer science department of the University of Central Missouri.