the man who loved numbers (11) an unlikely pair

Graham and Erdös would seem an . Although Graham is one of the world's mathematicians, he did not, like Erdös, renounce body for mind. , he continues to push both . At 6ft 2in, Graham looks at least a decade younger than his 62 years. He can juggle six balls and is a former president of the International Jugglers' Association. He is an trampolinist, who through college as a circus acrobat.

In the middle of solving mathematical problems, he will spring into a , grab stray objects and juggle them, or jump up and down on the pogo stick he keeps in his office. "You can do mathematics anywhere," said Graham. "I once had a into a stubborn problem in the middle of a back with a triple twist on my trampoline."

Erdös and Graham met in 1963 in Boulder, Colorado, at a conference on number theory and immediately began collaborating, writing 27 papers and one book together. That meeting was also the first of many spirited athletic the two men had.

"I remember thinking when we met that he was kind of an old guy," said Graham, "and I was that he beat me at Ping-Pong. That got me to the game seriously." Graham bought a machine that served Ping-Pong balls at very high speeds.