The correct form is 11th, not 11st. This rule applies because ordinal numbers in English always end with the last two letters of the word written out fully. For example, “first” ends in “st,” “second” ends in “nd,” “third” ends in “rd,” and “ fourth ” ends in “th.”
jagranjosh.com: Class 11th Elective English Syllabus 2024-25: Download Revised PDF for ISC Class 11 Elective English
Class 11th Elective English Syllabus 2024-25: Download Revised PDF for ISC Class 11 Elective English
Even though 11th, 12th, and 13th end in 1, 2, and 3, they still take “th” because of their special spelling and pronunciation: 11th, 12th, 13th (not 11st, 12nd, or 13rd)
Correct spelling, explanation: this ordinal number should be written as 11th because they don’t pronounce it with first at the end (which would then indicate -st suffix), but we pronounce it eleventh, so with -th at the end.
11th or eleventh is the ordinal version of the cardinal number 11. Now that you know how to spell 11th, you may also be interested to know that 11 is spelled eleven.
Correct spelling, explanation: 11th is an ordinal number and is correctly spelled with -th at the end because the full-word form is pronounced eleventh. THe suffix -st is similarly used with numbers that are pronounced with such a sound at the end (with the word first).
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.