Names of Numbers - Second Grade
What are Names of Numbers?
Concept: Numbers have different names! Cardinal numbers tell "how many" (1, 2, 3...) and Ordinal numbers tell "position" (1st, 2nd, 3rd...). We also write numbers in words!
What We'll Learn:
✓ Ordinal numbers (1st, 2nd, 3rd... up to 100th)
✓ Writing numbers in words (one, two, three...)
✓ Difference between cardinal and ordinal
✓ Using ordinals in everyday life
💡 Tip: Ordinals tell position in a line or order - like who finished the race first!
Cardinal Numbers vs Ordinal Numbers
Concept: It's important to know when to use cardinal numbers and when to use ordinal numbers!
📊 CARDINAL Numbers
Purpose: Tell HOW MANY
Used for: Counting, quantity
Examples:
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
In words:
one, two, three, four, five
Example sentences:
• I have 5 apples
• There are 20 students
• She is 7 years old
🏆 ORDINAL Numbers
Purpose: Tell POSITION/ORDER
Used for: Ranking, sequence
Examples:
1st, 2nd, 3rd, 4th, 5th, 6th, 7th, 8th, 9th, 10th
In words:
first, second, third, fourth, fifth
Example sentences:
• She came 1st in the race
• My birthday is on the 5th
• This is the 3rd floor
Quick Comparison
| Question | Cardinal | Ordinal |
|---|---|---|
| How many books? | 5 books ✓ | 5th book ✗ |
| Which floor? | 3 floor ✗ | 3rd floor ✓ |
| Count children | 10 children ✓ | 10th child ✗ |
💡 Tip: If you're counting "how many," use cardinal. If you're showing position, use ordinal!
1. Ordinal Numbers up to 10th
Concept: Ordinal numbers show the position or order of things. The first 10 ordinal numbers are special and must be memorized!
First 10 Ordinal Numbers
1st
first
2nd
second
3rd
third
4th
fourth
5th
fifth
6th
sixth
7th
seventh
8th
eighth
9th
ninth
10th
tenth
Special Ordinals (Must Memorize):
1st = first (not oneth!)
2nd = second (not twoth!)
3rd = third (not threeth!)
Note: From 4th onwards, most ordinals end in "-th"
📝 Visual Example: Race Winners
🥈
2nd
Second Place
🥇
1st
First Place
🥉
3rd
Third Place
💡 Tip: Remember 1st, 2nd, 3rd are special. From 4th onwards, add "-th" to the number!
2. Ordinal Numbers up to 100th
Concept: Once we know the pattern for 1-10, we can create ordinal numbers all the way to 100!
Pattern Rules:
Rule 1: Numbers ending in 1 → use "st" (except 11)
21st, 31st, 41st, 51st, 61st, 71st, 81st, 91st
Rule 2: Numbers ending in 2 → use "nd" (except 12)
22nd, 32nd, 42nd, 52nd, 62nd, 72nd, 82nd, 92nd
Rule 3: Numbers ending in 3 → use "rd" (except 13)
23rd, 33rd, 43rd, 53rd, 63rd, 73rd, 83rd, 93rd
Rule 4: All other numbers → use "th"
4th, 5th, 6th, 7th, 8th, 9th, 10th, 11th, 12th, 13th, 14th...
Ordinal Numbers by Tens
| Range | Examples | In Words |
|---|---|---|
| 11-19 | 11th, 12th, 13th, 14th, 15th | eleventh, twelfth, thirteenth... |
| 20-29 | 20th, 21st, 22nd, 23rd, 24th | twentieth, twenty-first... |
| 30-39 | 30th, 31st, 32nd, 33rd, 34th | thirtieth, thirty-first... |
| 40-49 | 40th, 41st, 42nd, 43rd, 44th | fortieth, forty-first... |
| 50-100 | 50th, 60th, 70th, 80th, 90th, 100th | fiftieth, sixtieth... hundredth |
Special Cases to Remember:
✓ 11th, 12th, 13th all end in "th" (not 11st, 12nd, 13rd)
✓ 20th = twentieth (not twentyth)
✓ 30th = thirtieth (not thirtyth)
✓ 40th = fortieth (not fourtyth - note the spelling!)
✓ 100th = hundredth
💡 Tip: Look at the last digit to decide if you use st, nd, rd, or th!
3. Writing Numbers up to 100 in Words
Concept: We can write numbers using words instead of digits! This is important for writing checks, formal documents, and stories.
Cardinal Numbers 1-20 in Words
1
one
2
two
3
three
4
four
5
five
6
six
7
seven
8
eight
9
nine
10
ten
11
eleven
12
twelve
13
thirteen
14
fourteen
15
fifteen
16
sixteen
17
seventeen
18
eighteen
19
nineteen
20
twenty
Tens Numbers in Words:
10 = ten
20 = twenty
30 = thirty
40 = forty
50 = fifty
60 = sixty
70 = seventy
80 = eighty
90 = ninety
100 = hundred
📝 How to Write Two-Digit Numbers
Example 1: Write 45 in words
Step 1: Tens = 40 = forty
Step 2: Ones = 5 = five
Step 3: Connect with hyphen (-)
45 = forty-five
Example 2: Write 73 in words
70 = seventy
3 = three
73 = seventy-three
Example 3: Write 100 in words
100 = one hundred
Important Rules:
✓ Always use a hyphen (-) between tens and ones
✓ Forty (not fourty) - watch the spelling!
✓ Numbers ending in zero are easy: 30 = thirty, 50 = fifty
✓ Always start with capital letter in sentence
💡 Tip: Practice writing your age, house number, and favorite numbers in words!
🎯 Tips for Names of Numbers Success 🎯
- ✓ Memorize 1st, 2nd, 3rd - they are special ordinals
- ✓ Remember: 11th, 12th, 13th all use "th" (not st, nd, rd)
- ✓ For ordinals, look at the last digit: 1→st, 2→nd, 3→rd, others→th
- ✓ Use cardinal (5) for "how many," ordinal (5th) for "position"
- ✓ When writing numbers in words, use hyphens (forty-five)
- ✓ Practice with calendars, floors, and race positions!
⭐ You're a Number Names Expert! ⭐
Fantastic work learning about names of numbers! You now know the difference between cardinal and ordinal numbers, can use ordinals up to 100th, can write any number up to 100 in words, and understand when to use each type. These skills help you in everyday life - from telling the date to describing positions in a line. Keep practicing and you'll be a number naming champion! You're doing wonderful!