You write "third" in numbers as 3rd.
The suffix "-rd" is added to the numeral 3 to represent its ordinal form. This is a common convention in English to indicate position or order in a sequence. Other examples include:
- First = 1st
- Second = 2nd
- Fourth = 4th
- Fifth = 5th
- Sixth = 6th
- Seventh = 7th
- Eighth = 8th
- Ninth = 9th
- Tenth = 10th
- Eleventh = 11th
- Twelfth = 12th
- Thirteenth = 13th
- Twentieth = 20th
- Twenty-first = 21st
- Twenty-second = 22nd
- Twenty-third = 23rd
As you can see, generally "th" is added as a suffix, but numbers ending in 1, 2, or 3 follow the pattern of "st," "nd," and "rd," respectively.
