Topics
Number System(Consolidating the Sense of Numberness)
Number System
Estimation
Ratio and Proportion
Algebra
Numbers in India and International System (With Comparison)
Geometry
Place Value
Mensuration
Natural Numbers and Whole Numbers (Including Patterns)
Data Handling
Negative Numbers and Integers
Number Line
HCF and LCM
Playing with Numbers
- Simplification of Brackets
- Finding Factors Using Rectangular Arrangements and Division
- Factors and Common Factors
- Multiples and Common Multiples
- Concept of Even and Odd Number
- Tests for Divisibility of Numbers
- Divisibility by 2
- Divisibility by 4
- Divisibility by 8
- Divisibility by 3
- Divisibility by 6
- Divisibility by 9
- Divisibility by 5
- Divisibility by 11
Sets
Ratio
Proportion (Including Word Problems)
Unitary Method
Fractions
- Concept of Fraction
- Types of Fractions
- Concept of Proper and Improper Fractions
- Concept of Mixed Fractions
- Like and Unlike Fraction
- Concept of Equivalent Fractions
- Conversion between Improper and Mixed fraction
- Conversion between Unlike and Like Fractions
- Simplest Form of a Fractions
- Comparing Fractions
- Addition of Fraction
- Subtraction of Fraction
- Multiplication of Fraction
- Division of Fractions
- Using Operator 'Of' with Multiplication and Division
- BODMAS Rule
- Problems Based on Fraction
Decimal Fractions
Percent (Percentage)
Idea of Speed, Distance and Time
Fundamental Concepts
Fundamental Operations (Related to Algebraic Expressions)
Substitution (Including Use of Brackets as Grouping Symbols)
Framing Algebraic Expressions (Including Evaluation)
Simple (Linear) Equations (Including Word Problems)
Fundamental Concepts
Angles (With Their Types)
Properties of Angles and Lines (Including Parallel Lines)
Triangles (Including Types, Properties and Constructions)
Quadrilateral
Polygons
The Circle
Symmetry (Including Constructions on Symmetry)
Recognition of Solids
Perimeter and Area of Plane Figures
Data Handling (Including Pictograph and Bar Graph)
Mean and Median
- Introduction
- Sum of First n Odd Numbers
- Sum of Natural Numbers
- Sum of First n Even Numbers
- Repeated 1's Pattern
- Key Points Summary
Introduction
Patterns help us see order in numbers and predict what comes next. They're like mathematical magic tricks that work every time! Here are four important patterns that will amaze you.
Sum of First n Odd Numbers
Step-by-Step Understanding:
- Start with 1 (that's 1² = 1)
- Add the next odd number, 3: 1 + 3 = 4 (that's 2² = 4)
- Add the next odd number, 5: 1 + 3 + 5 = 9 (that's 3² = 9)
- Add the next odd number, 7: 1 + 3 + 5 + 7 = 16 (that's 4² = 16)
The sum of the first n odd numbers always equals n² (a perfect square).
Sum of Natural Numbers
Step-by-Step Understanding:
- Natural numbers: 1, 2, 3, 4, 5, ...
- Formula: 1 + 2 + 3 + ... + n = `"n(n + 1)"/ 2`
- Example: 1 + 2 + 3 + 4 + 5 = `"5 × (5 + 1)" / "2"` = 15

- When Triangle 1 and Triangle 2 are combined, they form a rectangle of dots:
Rows: 6 (the total number of natural numbers, n)
Columns: 7 (each row sums to n+1) - So, the rectangle contains n(n+1) dots in total.
- Since this rectangle is formed by two identical triangles, the number of dots in one triangle is
- `"n(n + 1)"/ 2`
Sum of First n Even Numbers
Step-by-Step Understanding:
- Even numbers: 2, 4, 6, 8, 10, ...
- Formula: 2 + 4 + 6 + ... + 2n = n(n + 1)
- Example: 2 + 4 + 6 + 8 + 10 = 5 × 6 = 30
| n | First, n Even Numbers | Sum | Formula: n(n+1) |
|---|---|---|---|
| 1 | 2 | 2 | 1 × 2 = 2 |
| 2 | 2 + 4 | 6 | 2 × 3 = 6 |
| 3 | 2 + 4 + 6 | 12 | 3 × 4 = 12 |
| 4 | 2 + 4 + 6 + 8 | 20 | 4 × 5 = 20 |
| 5 | 2 + 4 + 6 + 8 + 10 | 30 | 5 × 6 = 30 |
Repeated 1's Pattern
When you multiply numbers made of repeated 1's (like 1, 11, 111, etc.), the result follows a mirrored pattern.
- For example:
1 × 1 = 1
11 × 11 = 121
111 × 111 = 12321
1111 × 1111 = 1234321, and so on.
Key Points Summary
-
Odd Numbers: 1 + 3 + 5 + ... + (2n−1) = n²
-
Natural Numbers: 1 + 2 + 3 + ... + n = n(n+1)/2
-
Even Numbers: 2 + 4 + 6 + ... + 2n = n(n+1)
-
Repeated 1's: Create palindromic patterns when multiplied
Test Yourself
Shaalaa.com | Patterns in Whole Numbers
Related QuestionsVIEW ALL [2]
Study the pattern:
| 1 × 8 + 1 = 9 |
| 12 × 8 + 2 = 98 |
| 123 × 8 + 3 = 987 |
| 1234 × 8 + 4 = 9876 |
| 12345 × 8 + 5 = 98765 |
Write the next two steps. Can you say how the pattern works?
(Hint: 12345 = 11111 + 1111 + 111 + 11 + 1).
