Concept of Variables (7)

Introduce the concept of variables as a way of representing numbers using letters (ACMNA175)

LO: To understand the concept of variables used to represent numbers.


  • What a variable is.
  • That a variable can be used to replace a number


  • That variables can be used to replace a number


  • I can replace a number with a variable

Essential Questions:

  • What is a variable?
  • How can variables replace numbers?

What are variables?

Variables are “missing values“.
A pronumeral is a letter or symbol that is used in place of a number.

In real life, someone might ask you, something plus 5 makes 10. What is something?

In Numeracy terms, mathematicians are a bit lazy so they want to make it as easy as possible, so they write “x” in place of something, so that it looks more like (x + 5 = 10).

Why do we need to use letters?
-letters are easier to write than something.
-if there are more than 1 missing value, then we can use multiple letters.

In some equations, you might have multiple variables, like I = PRT or E = MC^2 or S = D/T

Operations with Variables

7x is the same as 7 times x.
x/5 is the same as x divided 5.

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