Correct spelling, explanation: 28th is the ordinal number that consists of twenty and eighth. Th is a word-forming element that makes ordinal numbers from the number fourth and so forth. We can learn that this element has already been used in Old English and later in Proto-Germanic as the. It clearly shows that when we make ordinal numbers 8th or 28th, 38th, etc., we add th, not rd. This is the reason why 28th is correct, not 28rd.

Definition of 28th:
28th – the ordinal number next after the twenty-seventh,
We won’t have met until 28th January next year.
We received the payment on the 28th of June.
Contemporary rooms are located on the 28th floor.

Incorrect spelling, explanation: the suffix rd is added only to the number 3 in order to create an ordinal number, meaning the third position or 23, 33, 43, and so on. English learners can sometimes write the incorrect form of the ordinal number 28th as 28rd. However, the rule says that we add th to numbers from 4, 5, 6, etc., and rd to number 3 in order to create the ordinals. Therefore, 28rd is incorrect.

Incorrect spelling

Incorrect spelling