FTCE Pre-K Prekindergarten PK-3 Practice Exam

When students understand the concept of commutativity in addition, they grasp that the order in which two numbers are added does not affect the sum. For example, if they know that 2 + 3 = 5, they can also understand that 3 + 2 = 5. This property significantly reduces the number of individual addition facts they need to memorize.

In a standard addition context for single-digit numbers (0 through 9), there are 100 potential combinations. However, because of commutativity, each pair of addends yields two facts that are essentially the same. This allows for substantial reductions in the total number of unique facts that need to be learned.

By assessing the pairs that can be formed with the digits 0 through 9, we find that there are 55 unique addition facts when commutativity is taken into account, as it pairs each distinct combination without repetition. Thus, understanding this property means that students only need to learn 55 basic addition facts, which streamlines their learning process in mathematics.