Class 2 Notes - Number Sense
Introduction to Number Sense
Number sense is the foundation of all mathematical understanding. In Class II, students build on what they have already learned about numbers in Class I and begin to explore larger numbers, their values, positions, and operations.
Key Concepts in Number Sense
1. Understanding Numbers up to 1000
In the Indian place value system, numbers are written in terms of ones, tens, and hundreds.
Example: In the number 345:
3 × 100 = 300
4 × 10 = 40
5 × 1 = 5
Total = 345
2. Writing Numbers in Words and Figures
| Number | In Words |
|---|
| 100 | One hundred |
| 205 | Two hundred five |
| 999 | Nine hundred ninety-nine |
Reading and Writing Numbers up to 1000
783 → Seven hundred eighty-three
420 → Four hundred twenty
Place Value and Face Value
Place Value: The value of a digit depending on its position.
Face Value: The digit itself.
In 472:
4 → Place Value = 400, Face Value = 4
7 → Place Value = 70, Face Value = 7
Expanded Form of Numbers
826 = 800 + 20 + 6
340 = 300 + 40 + 0
Activity: Pick any 3-digit number and write its expanded form.
Comparing Numbers
Symbols: > Greater than, < Less than, = Equal to
524 > 320
208 < 812
657 = 657
Tip: The alligator always eats the bigger number!
Ordering Numbers
Ascending Order
321, 433, 556, 678
Descending Order
912, 789, 543, 100
Odd and Even Numbers
- Even: End in 0, 2, 4, 6, 8
- Odd: End in 1, 3, 5, 7, 9
Skip Counting
- By 2s: 2, 4, 6, 8, 10...
- By 5s: 5, 10, 15, 20...
- By 10s: 10, 20, 30, 40...
Before, After, and Between
- Before 304 → 303
- After 799 → 800
- Between 209 and 211 → 210
Forming Numbers
Use digits 3, 7, 1:
Greatest: 731
Smallest: 137
Rounding Numbers
43 → 40
78 → 80
Tip: 0–4 round down, 5–9 round up
Ordinal Numbers
- 1st – First
- 2nd – Second
- 3rd – Third
- 4th – Fourth
Number Patterns
2, 4, 6, 8 → 10
100, 90, 80 → 70
Estimating Numbers
Estimation is giving an approximate value.
Use of Numbers in Daily Life
- Reading page numbers
- Clocks
- Counting money
- Phone numbers
Fun Activities
- Number cards from 100 to 999
- Dice games
- Number hunt at home
- Draw place value houses
- Math stories
Common Mistakes
- Confusing place value and face value
- Spelling mistakes in number names
- Comparing digits instead of numbers
Assessment Questions
Objective:
- Place value of 3 in 435?
- Write 892 in words
- Number name for 670
- Which is greater: 783 or 738?
Short Answer:
- 3 numbers between 150 and 160
- Arrange: 208, 802, 820 (ascending)
- Circle even numbers: 13, 24, 35, 42, 57
Projects:
- Place value chart with matchsticks
- Snakes & ladders with skip counting
- Birthday chart with ordinal numbers
Conclusion
This chapter helps students understand how numbers work in real life. With activities and practice, children can develop confidence in math.