Ordinal numbers are the numbers that show placement in a sequence or line. They are written as 1st, 2nd, 3rd and so on. There can also be written as words including fourth, fifth, and sixth. They are known for having the th on the end of the number or word. However, st is added to one or the first number. These numbers are based on the cardinal numbers but ordinal numbers are used to refer to when something happened. For example, some people use first, second and third in an essay to explain when each event occurred. Sometimes, the number is placed above items in a line.