一个多边形的内角和等于它的外角和的5倍，那么此多边形的边数为______．

信息归纳（本题共5小题，每小题2分，共10分）
阅读下面材料，完成信息卡。
Beethoven, a famous musician in the world, was born in Germany in 1770. In his childhood Beethoven didn’t have a happy life. His father was a singer. When he was only four, his father began to make him practice hour after hour on different musical instruments. If he did not put his heart into it, his father would beat him or make it hard on him.
Beethoven loved music an he learned so fast that he was able to go around to give concerts, when he was only a boy of eleven. At the age of seventeen, he won high praise from Mozart, the great musician at that time.
Beethoven was often poor an ill during his life. After one illness, he suddenly found himself deaf. At that time he was only thirty-one. It was a blow (打击) to him indeed.
But he still went on working and writing music pieces. To people’s surprise, some of his best pieces were written after he lost his hearing.
In 1827, leaving more than 300 pieces, the great musician died. But his name is still remembered to his day.
Information Card

小题1:The birthplace of Beethoven
小题2:The job of Beethoven
小题3:The age when he won high praise from Mozart
小题4:Thing that happened at the age of 31
小题5:The year when Beethoven died