Class 5 | CBSE, NCERT & ICSE
Look around you ā patterns are everywhere! The petals of a flower, the stripes on a tiger, the tiles on a floor, the rhythm of music, and even the way numbers behave. In mathematics, a pattern is a set of numbers or shapes that follow a definite rule.
A sequence is a list of numbers written in a specific order, where each number follows a rule. For example: 2, 4, 6, 8, 10, ... ā can you see the pattern? Each number is 2 more than the previous one. Finding patterns helps us predict what comes next, and this skill is used in science, computer programming, music, and art!
In an arithmetic pattern, you add (or subtract) the same number each time. This constant is called the common difference.
| Pattern | Rule | Common Difference | Next 3 Terms |
|---|---|---|---|
| 5, 10, 15, 20, ... | Add 5 | +5 | 25, 30, 35 |
| 3, 7, 11, 15, ... | Add 4 | +4 | 19, 23, 27 |
| 100, 92, 84, 76, ... | Subtract 8 | ā8 | 68, 60, 52 |
| 1.5, 3.0, 4.5, 6.0, ... | Add 1.5 | +1.5 | 7.5, 9.0, 10.5 |
Example 1: Find the next 3 terms: 7, 12, 17, 22, ...
Solution: Common difference = 12 ā 7 = 5 (adding 5 each time)
Next terms: 22 + 5 = 27, 27 + 5 = 32, 32 + 5 = 37
Answer: 7, 12, 17, 22, 27, 32, 37
Example 2: Find the rule and the missing number: 95, 86, 77, ___, 59, 50
Solution: Difference = 86 ā 95 = ā9 (subtracting 9 each time)
Missing number = 77 ā 9 = 68
In a geometric pattern, you multiply (or divide) by the same number each time. This constant is called the common ratio.
| Pattern | Rule | Common Ratio | Next 3 Terms |
|---|---|---|---|
| 2, 6, 18, 54, ... | Multiply by 3 | Ć3 | 162, 486, 1458 |
| 5, 10, 20, 40, ... | Multiply by 2 | Ć2 | 80, 160, 320 |
| 10000, 1000, 100, 10, ... | Divide by 10 | Ć·10 | 1, 0.1, 0.01 |
| 3, 12, 48, 192, ... | Multiply by 4 | Ć4 | 768, 3072, 12288 |
Example 3: Find the next 2 terms: 4, 12, 36, 108, ...
Solution: 12 Ć· 4 = 3, 36 Ć· 12 = 3, 108 Ć· 36 = 3 ā Common ratio = Ć3
Next: 108 Ć 3 = 324, 324 Ć 3 = 972
Answer: ..., 108, 324, 972
A group of numbers repeats over and over.
Example 4: 1, 4, 9, 1, 4, 9, 1, 4, 9, ...
The group {1, 4, 9} repeats. The 10th term = 1 (start of 4th cycle).
A square number is the result of multiplying a number by itself: n à n = n²
| n | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
|---|---|---|---|---|---|---|---|---|---|---|
| n² | 1 | 4 | 9 | 16 | 25 | 36 | 49 | 64 | 81 | 100 |
Pattern in square numbers: The difference between consecutive squares is always odd: 4ā1=3, 9ā4=5, 16ā9=7, 25ā16=9, ... (differences: 3, 5, 7, 9, 11, ...)
Triangular numbers count dots arranged in triangles: 1, 3, 6, 10, 15, 21, 28, ...
Rule: Add 2, then 3, then 4, then 5, ... (add one more each time)
| Position | 1st | 2nd | 3rd | 4th | 5th | 6th | 7th | 8th |
|---|---|---|---|---|---|---|---|---|
| Number | 1 | 3 | 6 | 10 | 15 | 21 | 28 | 36 |
| How | 1 | 1+2 | 1+2+3 | 1+2+3+4 | 1+2+3+4+5 | +6 | +7 | +8 |
A cube number is n à n à n = n³. They represent the volume of cubes.
| n | 1 | 2 | 3 | 4 | 5 | 6 |
|---|---|---|---|---|---|---|
| n³ | 1 | 8 | 27 | 64 | 125 | 216 |
One of the most famous patterns in mathematics! Each number is the sum of the two numbers before it:
0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ...
Rule: Next term = Previous two terms added together
Did You Know? The Fibonacci sequence appears in nature! Sunflowers have 34 or 55 spirals, pinecones have 8 or 13 spirals, and many flowers have 3, 5, 8, or 13 petals. Indian mathematician Virahanka described this sequence around 700 CE ā centuries before Fibonacci!
Follow these steps:
| Step | What to Do | Example: 3, 7, 11, 15, 19, ... |
|---|---|---|
| 1 | Find the differences between consecutive terms | 7ā3=4, 11ā7=4, 15ā11=4, 19ā15=4 |
| 2 | If differences are constant ā Arithmetic (add/subtract) | Yes! Constant difference = 4 |
| 3 | If differences are NOT constant, find ratios | Not needed here |
| 4 | If ratios are constant ā Geometric (multiply/divide) | ā |
| 5 | If neither, look for other rules (Fibonacci, squares, two-step) | ā |
Some patterns use two operations together:
Example 5: 2, 5, 11, 23, 47, ...
Solution: Differences: 3, 6, 12, 24 ā the differences are doubling!
Or think: each term = previous Ć 2 + 1
Check: 2Ć2+1=5 ā, 5Ć2+1=11 ā, 11Ć2+1=23 ā, 23Ć2+1=47 ā
Next term: 47 Ć 2 + 1 = 95
Example 6: 1, 4, 9, 16, 25, 36, ...
Solution: These are 1², 2², 3², 4², 5², 6² ā square numbers!
Next term: 7² = 49
Example 7: 2, 6, 12, 20, 30, 42, ...
Solution: Differences: 4, 6, 8, 10, 12 ā differences increase by 2 each time
Next difference = 14. Next term = 42 + 14 = 56
(These are n Ć (n+1): 1Ć2=2, 2Ć3=6, 3Ć4=12, 4Ć5=20, 5Ć6=30, 6Ć7=42, 7Ć8=56)
Multiplication tables are full of hidden patterns!
| 9 Ć n | Answer | Tens Digit | Ones Digit | Digit Sum |
|---|---|---|---|---|
| 9 Ć 1 | 09 | 0 | 9 | 0+9 = 9 |
| 9 Ć 2 | 18 | 1 | 8 | 1+8 = 9 |
| 9 Ć 3 | 27 | 2 | 7 | 2+7 = 9 |
| 9 Ć 4 | 36 | 3 | 6 | 3+6 = 9 |
| 9 Ć 5 | 45 | 4 | 5 | 4+5 = 9 |
| 9 Ć 6 | 54 | 5 | 4 | 5+4 = 9 |
Patterns: Tens digit goes up (0,1,2,3,...), ones digit goes down (9,8,7,6,...), and digit sum is always 9!
A magic square is a grid where every row, column, and diagonal adds up to the same number (the magic constant).
3Ć3 Magic Square (numbers 1-9, magic constant = 15):
| 2 | 7 | 6 |
| 9 | 5 | 1 |
| 4 | 3 | 8 |
Every row, column, and diagonal = 15
Did You Know? India has one of the oldest known magic squares! A 4Ć4 magic square is carved in the Parshvanath temple in Khajuraho (12th century). Its magic constant is 34. Ancient Indian mathematicians were fascinated by number patterns!
| Where | Pattern | Type |
|---|---|---|
| Sunflower seeds | Fibonacci spirals (34, 55) | Fibonacci |
| Honeycomb | Hexagonal pattern repeats | Repeating geometric |
| Seasons | Summer, Monsoon, Winter, Spring ā repeats | Repeating |
| Cricket overs | 6 balls per over, score increases | Arithmetic |
| Bank interest (compound) | Amount doubles periodically | Geometric |
| Rangoli designs | Symmetrical repeating patterns | Repeating / symmetry |
| Train timings | Arrive every 15 minutes | Arithmetic (+15) |
| Word | Meaning |
|---|---|
| Pattern | A set of numbers/shapes that follow a definite rule |
| Sequence | An ordered list of numbers following a rule |
| Term | Each number in a sequence |
| Common Difference | The constant amount added/subtracted in arithmetic patterns |
| Common Ratio | The constant multiplier in geometric patterns |
| Arithmetic Pattern | Add or subtract the same number each time |
| Geometric Pattern | Multiply or divide by the same number each time |
| Fibonacci Sequence | Each term = sum of two previous terms |
| Square Number | n Ć n (1, 4, 9, 16, 25, ...) |
| Triangular Number | 1, 3, 6, 10, 15, ... (sum of first n natural numbers) |
| Magic Square | Grid where all rows, columns, diagonals have the same sum |
Finished learning? Now test what you know!