How do you know your weight? Maybe you can stand on a scale and read the number very soon. However, when something is very huge, like an elephant, how do we weigh it?
A long time ago a man whose name was Cao Cao, faced the same question. He got an elephant from his friend. But nobody knew the weight of the elephant. Cao Cao had a son named Cao Chong. He was only six years old. He said to his father, "Let me try!" The little child asked a man to get the elephant onto a boat on a river. The boat went down a little, and the man marked the water level on the boat. Then the little boy asked some strong men to put rocks on the boat. When the water reached the mark, he said, "Stop! Now let's weigh these rocks and then we'll know the weight of the elephant." Cao Cao was very happy to have such a clever son.
