Ordinal numbers to 100th

key notes:

🔢 What Are Ordinal Numbers?

• Ordinal numbers tell the position or order of things in a list.
• They answer the question: Which one?

🧠 Examples:

• 1st = First
• 2nd = Second
• 3rd = Third
• 4th = Fourth
• …
• 100th = Hundredth

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🧮 How Are Ordinal Numbers Written?

Number	Ordinal Number	Word Form
1	1st	First
2	2nd	Second
3	3rd	Third
4	4th	Fourth
10	10th	Tenth
21	21st	Twenty-first
35	35th	Thirty-fifth
100	100th	Hundredth

✅ Notice:

• Numbers ending in 1 (except 11) → use st (1st, 21st, 31st)
• Numbers ending in 2 (except 12) → use nd (2nd, 22nd)
• Numbers ending in 3 (except 13) → use rd (3rd, 23rd)
• All others → use th (4th, 11th, 13th, 14th, …)

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🏁 Where Do We Use Ordinal Numbers?

• Race results: 1st place, 2nd place, 3rd place
• Dates: January 1st, July 4th
• Positions: The 5th student in line
• Floors: 10th floor of a building

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📝 Practice Time

Write the ordinal number and word form:

1. 7 → ______ → __________
2. 12 → ______ → __________
3. 21 → ______ → __________
4. 43 → ______ → __________
5. 100 → ______ → __________

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🎯 Key Points to Remember

✔ Ordinal numbers show position, not quantity
✔ Use correct suffixes: st, nd, rd, th
✔ Special cases: 11th, 12th, 13th all end in th
✔ You can go up to the 100th position

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🧩 Fun Class Activity: “Ordinal Race”

🚦Write the names of 10 students on the board.
Ask: “Who is in 1st place? Who is in 4th place?”
Mix the names and repeat the activity!

Learn with an example

Let’s practice!