Addition and Subtraction Strategies (use of properties)

Properties of addition:

1) Changing order of addends does not change the sum.

For example: 1 + 2 = 2 + 1

2) Three or more numbers can be added in any order, no matter how the numbers are grouped.

For example: (1 + 2) + 3 = 1 + (2 + 3)

3) When zero is added to any number, the sum is that number itself.

For example: 5 + 0 = 5

4) When a number is subtracted from itself, the difference is zero.

For example: 3 – 3 = 0