Paul Sloane was born in Scotland. He studied engineering at Cambridge University and works in software marketing. His first book, Lateral Thinking Puzzlers , was published by Sterling in 1991 and has gone on to become a bestseller.   Des MacHale was born in County Mayo, Ireland, and is Associate Professor of Mathematics at University College in Cork. He and his wife, Anne, have five children. He is the author of over 40 books, including one on the John Ford cult film The Quiet Man and another on George Boole of Boolean algebra fame.   Following a chance meeting between Sloane and MacHale in 1991, the two have collaborated on many popular books of lateral-thinking puzzles, all published by Sterling.