- 1st: first,
- 2nd: second,
- 3rd: third,
- 4th: fourth,
- 5th: fiveth,
- 6th: sixth,
- 7th: seventh,
- 8th: eighth,
- 9th: ninth,
- 10th: tenth
- 11th: eleventh,
- 12th: twelfth,
- 13th: thirteenth,
- 14th: fourteenth,
- 15th: fifteenth,
- 16th: sixteenth,
- 17th: seventeenth,
- 18th: eighteenth,
- 19th: nineteenth,
- 20th: twentieth
- 21st: twenty first,
- 22nd: twenty second,
- 23: twenty third,
- 24th: twenty fourth,
- 25: twenty fiveth,
- 26: twenty sixth,
- 27: twenty seventh,
- 28: twenty eighth,
- 29: twenty ninth,
- 30: thirtieth,
- 31: thirty first
Đây là kiến thức căn bản trong Tiếng Anh các bạn phải luôn ghi nhớ.