倍数

例句：

1. 1.If you double the number of students, you will have twice as many students as before.
   如果你将学生人数加倍，你将会有原来的两倍多的学生。
2. 2. The cost of materials has tripled since last year.
   材料的成本自去年起已经翻了一番。
3. 3.The population of the city has increased by 50% in the past decade.
   过去十年间，该市的人口增加了50%。