This is the 5319th most frequent Chinese word.
九百
Nine hundred.
Here, '九百' specifies the price of an item in the currency RMB.
我今天买了一台九百元的手机。
I bought a cellphone for 900 RMB today.
In this example, '九百' refers to the amount or count, specifically the number of pages.
这本书的总字数超过九百页。
This book's total page count exceeds 900 pages.
This usage of '九百' indicates a point in time, specifically duration in years.