What is the addition rule?

Since ancient times, mathematicians have used rules that apply to number operations to help solve addition problems.  The commutative property means that when you add two numbers together, the order you add them does not matter, so 2 + 4 = 6 and 4 + 2 = 6.  The associative property means that the grouping of numbers does not matter when you are adding a series of numbers together so that 3 + (4 + 2) = (3 + 4) = 2.  The addition property of zero means that any number plus zero equals the same as the original number.