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Patterns in Mathematics - Relation to Number Sequences

Grade 6CBSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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A number pattern is a sequence of numbers that follows a specific rule. For example, in the sequence 2,4,6,8,…2, 4, 6, 8, \dots, each number increases by 22.

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The position of a number in a sequence is often denoted by nn. The first term is at n=1n=1, the second at n=2n=2, and so on.

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A common rule in Grade 6 involves finding the nthn^{th} term by relating the position nn to the value of the term. For example, if the sequence is 5,10,15,…5, 10, 15, \dots, the rule is 5×n5 \times n.

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Patterns can be observed in geometric shapes made of matchsticks. If one triangle requires 33 sticks and two triangles (sharing one side) require 55 sticks, the pattern follows the rule 2n+12n + 1.

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Square numbers are patterns formed by multiplying a number by itself: 1,4,9,16,…1, 4, 9, 16, \dots which is represented as n2n^2 or n×nn \times n.

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Triangular numbers are numbers that can form an equilateral triangle: 1,3,6,10,…1, 3, 6, 10, \dots.

📐Formulae

General Rule for Arithmetic Sequence=a+(n−1)d\text{General Rule for Arithmetic Sequence} = a + (n - 1)d

Matchstick rule for squares (separate)=4n\text{Matchstick rule for squares (separate)} = 4n

Matchstick rule for squares (joined)=3n+1\text{Matchstick rule for squares (joined)} = 3n + 1

Matchstick rule for triangles (joined)=2n+1\text{Matchstick rule for triangles (joined)} = 2n + 1

Sum of first n odd numbers=n2\text{Sum of first } n \text{ odd numbers} = n^2

💡Examples

Problem 1:

Observe the pattern 7,14,21,28,…7, 14, 21, 28, \dots and find the 20th20^{th} term.

Solution:

n=20n = 20, Rule =7×n= 7 \times n. Therefore, 7×20=1407 \times 20 = 140.

Explanation:

Each term in the sequence is a multiple of 77. To find any term, we multiply its position nn by 77.

Problem 2:

A pattern is formed using matchsticks to make the letter 'L'. One 'L' uses 22 sticks, two 'L's use 44 sticks, and three 'L's use 66 sticks. Write the rule and find how many sticks are needed for 5050 'L's.

Solution:

Rule =2n= 2n. For n=50n = 50, sticks =2×50=100= 2 \times 50 = 100.

Explanation:

Since each 'L' requires 22 sticks, the total number of sticks is twice the number of letters formed.

Problem 3:

Find the next two terms in the sequence: 1,3,5,7,…1, 3, 5, 7, \dots

Solution:

The next terms are 99 and 1111.

Explanation:

The sequence consists of consecutive odd numbers. The rule is to add 22 to the previous term, or the nthn^{th} term is given by 2n−12n - 1.