How would one multiply out brackets?

If asked to multiply out a set of brackets, one must remember to multiply each term in a set of brackets by every term in the other set of brackets. For example, (x+2)(x-4) = x²+2x-4x-8 = x²-2x+8. An incorrect answer would be x²+2x-4 where I have erroneously only multiplied the first term in the second bracket by the first bracket.