In English, the number nine is commonly expressed as "nine" or "9". The number nine is derived from the Old English word "nigon", which comes from the Proto-Germanic word "newun". Here are some example sentences using the number nine in English:

I have nine apples in my basket. (我的篮子里有九个苹果。)

The ninth chapter of the book is the most interesting. (这本书的第九章最有意思。)

The team has won nine games in a row. (这支队连续赢了九场比赛。)