The professor was intent upon giving his class a mental exercise:
"If Philadelphia is 100 miles from New York," said he, "and Chicago is 1000 miles from Philadelphia and Los Angles is 2000 miles from Chicago, how old am I?"
One student raised his hand and when called upon said,
"Professor you're 44.."
"You're absolutely correct, but tell me, how did you arrive at the answer so quickly?"
"You see professor, I have a brother; he's 22, and he's only half nuts ..."