List of Cardinal and Ordinal Numbers

• Cardinal numbers refer to the size of a group.
  I am twenty years old. I have four friends.
• Ordinal numbers refer to a position in a series.
  My first friend is a student. Today is his nineteenth birthday.
• Any ordinal name that doesn't end in st, nd, rd (as in "first", "second", or "third"), ends in th.
• All compound numbers from twenty-one through ninety-nine should be separated by a hyphen (twenty-two, seventy-first).
• A comma is optional with four-digit numbers but required with five-digit numbers (3000   30,000)

Standard English Language Rules for Numbers: English Numerals Rules for Writing Numbers

Spelling Quizzes Cardinal Numbers Ordinal Numbers