What is a Variable?

In algebra, a variable is a symbol, usually a letter, that represents a number. We use variables when we don't know the exact value of something. For example, if you have 'x' apples, 'x' is the variable. It could be 1, 5, or 100 apples!

Why Use Variables?

Variables let us write general rules and formulas. A very famous formula is E=mc². Here, E, m, and c are all variables. 'E' stands for energy, 'm' for mass, and 'c' for the speed of light. This simple equation describes a fundamental principle of the universe, all thanks to variables.

A simpler example: the perimeter of a square is 4 times the length of one side. We can write this as P = 4s, where P is the perimeter and s is the side length. This works for any square, no matter its size.