A mathematician and a Wall street broker went to races.

The broker suggested to bet $10,000 on a horse.

The mathematician was sceptical, saying that he wanted first to understand the rules, to look on horses, etc.

The broker whispered that he knew a secret algorithm for the success, but he could not convince the mathematician. "You are too theoretical," he said and bet on a horse. Surely, that horse came first bringing him a lot of money.

Triumphantly, he exclaimed: "I told you, I knew the secret!" "What is your secret?" the mathematician asked. "It is rather easy. I have two kids, three and five year old. I sum up their ages and I bet on number nine." "But, three and five is eight," the mathematician protested. "I told you, you are too theoretical!" the broker replied, "Haven't I just shown experimentally, that my calculation is correct! 3+5=9!"