Tailoring
Abraham wanted a new suit, so he bought a nice piece of cloth and then tried to locate a tailor. The first tailor he visited looked at the cloth and measured Abraham, then told him the cloth was not enough to make a suit.
Abraham was unhappy with this opinion and sought another tailor. This tailor measured Abraham, then measured the cloth, and then smiled and said, "There is enough cloth to make a pair of trousers, a coat and a vest, please come back in a week to take your suit."
After a week Abraham came to take his new suit, and saw the tailor's son wearing trousers made of the same cloth. Perplexed, he asked, "Just how could you make a full suit for me and trousers for your son, when the other tailor could not make a suit only?"
"It's very simple," replied the tailor, "The other tailor has two sons."