In August 1859 Bernhard Riemann, a 32-year old mathematician,posed a deceptively simple question to the Berlin Academy: Is there a generalrule for figuring out how many prime numbers there are? More than 150 yearslater, the solution to this critical problem eludes our grasp.

Riemann initially believed that he was tackling a straightforward matter ofarithmetic. He started with something very simple. How many prime numbers --numbers that cannot be evenly divided except by themselves and 1 -- are thereless than twenty? The (easy) answer: there are eight: 2, 3, 5, 7, 11, 13, 17,and 19. He went on to contemplate how many there are less than 100... which ledhim to wonder how many there were less than a million... or even a trillion.

As the questions progressed and grew in scope and magnitude, the answers becameincreasingly elusive. But might there be some logical formula for calculatingthe answers? As long ago as the third century B.C., Euclid proved that no onecould ever find the "largest" prime number -- that they are infinite in number.What Riemann wanted to know was whether there was a pattern to the primes. Hedevoted his life to the search for this subtle but presumably precise pattern.Ultimately, it would become not only his obsession, but that of generations ofmathematicians up to the present day.

Alternating chapters of extraordinarily lucid mathematical exposition withchapters of biography and history, Prime Obsession is a fascinating andfluent account of an epic mathematical mystery that continues to challenge andexcite the world. Posited over a century ago, Riemann's hypothesis is anenduring intellectual feast for the cognoscenti and the curious alike -- eventoday, the solution is still eagerly sought since prime numbers are an essentialkey to both code making and code breaking. Not just a story of numbers andcalculations, Prime Obsession is the engrossing tale of a relentless huntfor an elusive proof -- and those who have been consumed by it.