$(X + Y)\times (X - Y) = X^2 - Y^2$

This is one of the shortened multiplication formulas.

As can be seen, this formula can be used when there is a multiplication between the sum of two particular elements and the subtraction between the two elements.

Instead of presenting them as a multiplication of sum and subtraction, it can be written $X^2 - Y^2$ and it expresses exactly the same thing. In the same way, if such an expression $X^2 - Y^2$ representing the subtraction of two squared numbers is presented to you, you can write it like this: $(X + Y)\times (X - Y)$** Pay attention:** the formula works both in non-algebraic expressions and in expressions that combine unknowns and numbers.