31th vs 31st: What’s the Correct Ordinal Number and How to Avoid the Mistake?
Is it 31st or 31th? If you’ve ever hesitated while writing ordinal numbers in English, you’re not alone. This is one of the most common spelling mistakes students make, especially when dealing with dates and numbers above 20.
In this post, we’ll clarify the correct form, explain why the mistake happens, and help you remember the rule with examples, tips, and a quick quiz.
What Does “31st” Mean?
“31st” is the correct ordinal form of the number 31. It is used to show position or order, such as dates, rankings, or steps in a sequence.
Examples:
- “Her birthday is on the 31st of July.”
- “He finished in 31st place in the race.”
What Does “31th” Mean?
“31th” is a spelling error. It does not exist in standard English. Some learners mistakenly assume that all ordinal numbers end in “-th,” but that’s not the case for numbers ending in 1, 2, or 3.
Key Differences: 31st vs 31th
| Form | Correct? | Use | Example |
|---|---|---|---|
| 31st | ✅ Yes | Ordinal number (thirty-first) | “My appointment is on the 31st.” |
| 31th | ❌ No | Incorrect form | “The event is on the 31th.” ❌ |
Common Mistakes
- ❌ Writing “31th” instead of “31st.”
- ❌ Assuming all ordinal numbers use “-th.”
- ✅ Remember: only 4th, 5th, 6th, etc. use “-th.”
Easy Tricks to Remember
- 📌 Numbers ending in 1 → st → 1st, 21st, 31st
- 📌 Numbers ending in 2 → nd → 2nd, 22nd
- 📌 Numbers ending in 3 → rd → 3rd, 23rd
- 📌 All others use th → 4th, 5th, 6th...
Quick Practice Exercise
Select the correct ordinal number for each sentence:
Bonus Resources
- Explore more spelling tips on AulaPlanet → Full category
- Cambridge Grammar: Ordinal Numbers
- Wikipedia: Ordinal Numbers in English
Conclusion
While “31th” may look logical, it is never correct in English. Always use 31st for the thirty-first position or date. Now that you know the rule, you can write ordinal numbers confidently and avoid one of the most common spelling traps.
📲 Practice more spelling and grammar rules with AulaPlanet and become a writing pro!
Frequently Asked Questions (FAQs)
No, “31th” is always incorrect. The correct form is “31st.”
“31st” is the ordinal number for thirty-one. It is used to describe position or dates.
Because 31 ends in 1, and ordinal numbers that end in 1 (except 11) take “st.”
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