In Greek legend, the mutton king of Tyre had a smart and beautiful princess named Dido. Dido lived a happy life in her kingdom, free and carefree, but it didn't last long. Unfortunately, her husband was killed by her brother, the King of Cyprus.

Poor Dido fled to the west coast of Africa. She wanted to live here, so she took out her jewels, jade articles and gold coins and planned to buy some land from the local chief Jabbas to build a house. Dido said to the chief, "I just need a place where cowhide is wrapped." The chief didn't think about how big a piece of leather bag could be, so he picked up a big bargain and readily agreed. Dido asked for a cow, killed it, skinned it, cut the cowhide into long strips and prepared to enclose it with cowhide. Dido thought, if this cowhide strip is circled into a rectangle, the circled place is not big enough, and the circled place is not big enough. It's better to change it into a circle, so that the circle is the largest. Then Dido suddenly thought that the land given to him by the chief was by the sea. If pimps can form a semicircle along the coast, this semicircle of land must be the largest.

Clever Didi replaces the land boundary with the natural coastline, which is equivalent to invisibly increasing the length of cowhide strips. So she circled a semicircle with cowhide strips, which was the largest area she could circle. Later, Dido established Carthage there. Today, the monument to Carthage is still preserved.

Cao Chong called elephants.

In the Three Kingdoms, Wang had a son named Cao Chong. Cao Chong was clever since childhood, and won the favor of Cao Cao. Cao Chong loves to think and is diligent in thinking. Only five or six years old, he can find a way to solve some problems that even adults are helpless.

One day, Sun Quan, the king of Wu, sent someone to give Cao Cao an elephant as a gift. There are no elephants in the north. When Cao Cao saw such a monster for the first time, he was very curious and asked the person who sent the elephant, "How heavy is this elephant?" The bearer replied, "Bi Guo has never weighed an elephant, and there is no way to weigh it, so I don't know how heavy the elephant is." I have long heard that Wang Wei is a little talented, and there are many advisers under him, all of whom are brilliant. Please find a way to weigh the elephant and let me learn the demeanor of a big country in the north. "

Cao Cao suddenly understood that this was a problem given to him by Sun Quan, and he must not lose this face and damage the national prestige. So he called the ministers together and ordered that whoever could weigh the elephant would be rewarded. Everyone racked their brains and thought hard. Some people said that a big stalk would be built, but Cao Cao retorted that even if it was built, no one could lift it. Some people say that it is necessary to cut the elephant into several pieces before it can be called zero. Cao Cao rebuked how it was possible to destroy the gift from the State of Wu in this way. People hold me back, but no one comes up with a practical solution.

Just when everyone was at a loss, Cao Chong Jr. suddenly came up to Cao Cao and said, "Father, don't worry, I have an idea. We can take the elephant to the boat first, make a mark on the side of the boat, then take the elephant away and transport the stone to the boat until the boat reaches the mark in front. At this time, the weight of the stone is equal to that of the elephant. Then, we will weigh the stones separately and add up these weights. Don't we know how heavy the elephant is? "

Cao Cao was overjoyed, and everyone marveled at Cao Chong's cleverness. In this way, the weight of the elephant was finally weighed out.