Skill: Apply the associative property

The associative property lets you regroup three or more whole numbers without changing the answer. The numbers stay in the same order; only the parentheses change.

For addition:

$$(a+b)+c=a+(b+c)$$

Example

Find:

$$18+25+75$$

Group the numbers that are easy to add. Since $25+75=100$, regroup the expression:

$$18+(25+75)$$

Add inside the parentheses first:

$$18+100=118$$

So,

$$18+25+75=118$$

The grouping changed, but the order of the numbers did not. Changing the order would use the commutative property, not the associative property.