What is the commutative property of addition?

Answer 1

The commutative property of addition tells us that if "a" and "b" are numbers, then the value of the sum a + b is the same as the value of the sum b + a. A concrete example is that 9 + 1 = 1 + 9.

We say that 9 and 1 commute over the + sign: they can switch places and the value of the sum will remain the same.

The meaning of commutative remains the same in all mathematics. For example, we say multiplication of real numbers is commutative because a*b = b*a for any two real numbers "a" and "b".

You may wonder why we feel the need to name such an "obvious" property. As you study more advanced mathematics, you will come across certain operations that are not commutative, and certain types of mathematical objects that do not commute with + or *.