Correct spelling

11th

Correct spelling, explanation: 11th is the correct form because it’s an ordinal number eleventh – you can see that the word ends with th. So does the number form – 11th. 11st is wrong because st is added only to numbers ending with such sound (so de facto all numbers ending with first), for example, twenty-first 21st.

Definition of 11th:
numeral, the ordinal number between 10th and 12th
Can you imagine that it is his 11th time reading this book? For me, it’s super boring and he loves it!
I didn’t have to wait super long in the office, because the line went fast and I was 11th.


Incorrect spelling

11st

Incorrect spelling, explanation: this form is incorrect, and the correct one is 11th because 11st would have to end with st in the written form, while in fact it is eleventh so it ends with th. Therefore 11th is the correct form.

Incorrect spelling

11nd

Incorrect spelling

Incorrect spelling

11rd

Incorrect spelling