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K.1 Identify the properties of addition

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What are the properties of addition?

The properties of addition are rules that explain how numbers can be added in different ways without changing the sum.

How to Identify:
  • Look for changes in order, grouping, or the use of zero in addition problems.
  • Check if the sum remains the same after the change.
Examples:
  • 3 + 5 = 5 + 3
  • (2 + 4) + 6 = 2 + (4 + 6)
  • 7 + 0 = 7
Note

These properties work with all whole numbers and make addition easier to understand.

The commutative property of addition

The commutative property says that the order of addends can be changed without changing the sum.

How to Identify:
  • Check if the numbers switch places.
  • If the sum is the same, the commutative property is used.
Example:
  • 8 + 2 = 10
  • 2 + 8 = 10
Note

Think: “Changing the order does not change the answer.”

The associative property of addition

The associative property says that when three or more numbers are added, the way they are grouped does not change the sum.

How to Identify:
  • Look for parentheses that change the grouping of numbers.
  • If the total stays the same, the associative property is used.
Example:
  • (3 + 4) + 5 = 12
  • 3 + (4 + 5) = 12
Note

Parentheses show the grouping, but the final answer stays the same.

The identity property of addition

The identity property says that adding zero to a number does not change the number.

How to Identify:
  • Look for zero being added.
  • If the sum is the same number, the identity property is used.
Example:
  • 9 + 0 = 9
  • 0 + 12 = 12
Note

Zero is called the “additive identity” because it does not change the value of the number.

Using the properties of addition

We can use the properties of addition to solve problems more quickly and to check our work.

How to Identify:
  • Look for opportunities to switch order, change grouping, or use zero.
  • Check if the property makes solving easier.
Example:
  • 25 + 75 + 37 → Group (25 + 75) + 37 = 100 + 37 = 137
  • 46 + 0 = 46
Note

Using properties is like using shortcuts. They always work in addition and help you solve problems faster.