Both biographies of Erdös report that he was using speed (
amphetamine) throughout his life. He received it from a Hungarian doctor who was a friend. He slept only a couple of hours every night.
In 1979, his friend and mathematician Ronald Graham offered a $500 bet, challenging him to go without drugs for 30 days. Erdös met the challenge, but later complained bitterly that the progress of mathematics had been held up by this silly little bet.
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