CLASS 8 . MATHEMATICS . GANITA PRAKASH PART I . A SQUARE-AND-A-CUBE
Chapter 1 : A Square And A Cube
Ch 1
MATHEMATICS
CLASS 8
Square Numbers
A square number is the product of an integer multiplied by itself. Formally, for any integer \( n \), the square number is \( n^2 = n \times n \). Square numbers are also called perfect squares.
Formula Derivation
Given \( n \in \mathbb{Z} \), the square of \( n \) is \( n^2 \). For example, if \( n = 5 \), then \( 5^2 = 5 \times 5 = 25 \).
Worked Illustrations
Calculate the square of 7.
Step 1: Identify \( n = 7 \).
Step 2: Compute \( 7^2 = 7 \times 7 = 49 \).
Therefore, the square of 7 is 49.
Solved Examples
Example 1: Find the square of 12.
Step 1: \( n = 12 \).
Step 2: \( 12^2 = 12 \times 12 = 144 \).
Answer: 144
Example 2: Find the square of 15.
Step 1: \( n = 15 \).
Step 2: \( 15^2 = 15 \times 15 = 225 \).
Answer: 225
Practice Set
- Level 1 – Easy
- Find the square of 8.
- Find the square of 10.
- Find the square of 3.
- Level 2 – Moderate
- Find the square of 17.
- Find the square of 23.
- Find the square of 30.
- Level 3 – Challenging
- Find the square of 125.
- Find the square of 99.
- Find the square of 144.
Answer Key
- 8^2 = 64
- 10^2 = 100
- 3^2 = 9
- 17^2 = 289
- 23^2 = 529
- 30^2 = 900
- 125^2 = 15625
- 99^2 = 9801
- 144^2 = 20736
Quick Reference
| Number (n) | Square (n^2) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 9 |
| 4 | 16 |
| 5 | 25 |
Glossary
- Square Number: A number obtained by multiplying an integer by itself.
- Perfect Square: A square number that is the square of a natural number.
- Square Root: The inverse operation of squaring, denoted \( \sqrt{n} \).
Cube Numbers
A cube number is the product of an integer multiplied by itself three times. For any integer \( n \), the cube number is \( n^3 = n \times n \times n \). Cube numbers are also called perfect cubes.
Formula Derivation
Given \( n \in \mathbb{Z} \), the cube of \( n \) is \( n^3 \). For example, if \( n = 4 \), then \( 4^3 = 4 \times 4 \times 4 = 64 \).
Worked Illustrations
Calculate the cube of 5.
Step 1: Identify \( n = 5 \).
Step 2: Compute \( 5^3 = 5 \times 5 \times 5 = 125 \).
Therefore, the cube of 5 is 125.
Solved Examples
Example 1: Find the cube of 3.
Step 1: \( n = 3 \).
Step 2: \( 3^3 = 3 \times 3 \times 3 = 27 \).
Answer: 27
Example 2: Find the cube of 7.
Step 1: \( n = 7 \).
Step 2: \( 7^3 = 7 \times 7 \times 7 = 343 \).
Answer: 343
Practice Set
- Level 1 – Easy
- Find the cube of 2.
- Find the cube of 4.
- Find the cube of 1.
- Level 2 – Moderate
- Find the cube of 6.
- Find the cube of 9.
- Find the cube of 10.
- Level 3 – Challenging
- Find the cube of 15.
- Find the cube of 20.
- Find the cube of 25.
Answer Key
- 2^3 = 8
- 4^3 = 64
- 1^3 = 1
- 6^3 = 216
- 9^3 = 729
- 10^3 = 1000
- 15^3 = 3375
- 20^3 = 8000
- 25^3 = 15625
Quick Reference
| Number (n) | Cube (n^3) |
|---|---|
| 1 | 1 |
| 2 | 8 |
| 3 | 27 |
| 4 | 64 |
| 5 | 125 |
Glossary
- Cube Number: A number obtained by multiplying an integer by itself three times.
- Perfect Cube: A cube number that is the cube of a natural number.
- Cube Root: The inverse operation of cubing, denoted \( \sqrt[3]{n} \).
