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SAI International School
CLASS-VI
Mathematics
CHAPTER-11: Algebra
Lesson Notes-1

SUBTOPIC: Idea of constant and variables, formulation of general rule

Introduction to Algebra
 The study to use the letters and symbols in mathematics is called Algebra.
Algebra
Algebra is a part of mathematics in which the letter and symbols are used to represent
numbers in equations. It helps us to study about unknown quantities.
Matchstick Patterns

st
No. of matchsticks used to make 1 square = 4
nd
No. of matchsticks used to make 2 square = 7
rd
No. of matchsticks used to make 3 square = 10
So, the pattern that we observe here is 3n + 1

With this pattern, we can easily find the number of matchsticks required in any number
of squares.
Example
th
How many matchsticks will be used in the 50 figure?
Solution
3n + 1

3 × 50 + 1
= 151 matchsticks

The Idea of a Variable
Variable refers to the unknown quantities that can change or vary and are represented
using the lowercase letter of the English alphabets.

One such example of the same is the rule that we used in the matchstick pattern
3n + 1

Here the value of n is unknown and it can vary from time to time.

More Examples of Variables