Math Properties Review

Addition Properties Review

Why are properties helpful?

§  You can use them in during mental math to help you add the easiest numbers together first. 

§  Remember “compatible numbers”  1+9, 2+8, 3+7, 4+6, 5+5

Commutative Property AKA the “order” property

§  You can add numbers (addends) in any order and still get the same answer (sum).

§  Think:  commute or moving to a new spot. 

Examples:

6 + 7 = 7 + 6                                      28 + 17 = 17 + 28

WOW! You still get the same answer!

  13   =   13                                            45  =     45

Associative Property AKA the “grouping” property

   

§  When adding 3 numbers (addends), you can group any 2 addends first using parentheses, then add the third number, and still get the same answer (sum).

§  Remember, you do the “inside job” first – the problem in the parentheses.  Look for the easiest numbers to group together (compatible numbers) to put inside the parentheses.

§  Think:  you can associate (hang out) with any 2 numbers inside the parentheses

Examples:

Adding 6, 8, and 4:  You can group them in any way:

 

(6+8) + 4       or       (6+4) + 8      or         (4+8) + 6

14 + 4                            10 + 8                          12 + 6

 

WOW!   You still get the same answer!

 18                                    18                                 18

                       

Identity Property

§  You can add zero to any number, and still have the same number. 

§  Remember:  any number plus NOTHING, is still that number.

Examples: 

67 + 0 = 67                895 + 0 = 895                        43,091 + 0 = 43,091

Addition Vocabulary

§  Addends:  the numbers you are adding together

§  Sum:  the answer to an addition problem

SUM

7 + 3 = 10

ADDENDS