The number 90 is typically written as "ninety" in English. This word refers to the cardinal number that comes after 89 and before 91. In everyday language, we may use this word to describe a person's age if they are 90 years old. The word "ninety" is also used in measurements such as degrees, dollars, and pounds. For example, if the temperature is 90 degrees Fahrenheit, it is considered quite hot. In money, 90 dollars could buy a nice meal for two. In weight, 90 pounds might be the weight of a small child. Overall, the number 90 is a significant milestone in life, and the word "ninety" is frequently used in various contexts in the English language.