1.   Find the number that completes the number sentence. Then identify the property or rule.

(21 + 13) + 56 = 21 + (∅ + 56)
    A. 35; Subtraction Rule
    B. 13; Commutative Property of Addition
    C. 13; Associative Property of Addition
    D. 21; Identity Property of Addition
    Hint
  2.   Find the number that completes the number sentence. Then identify the property or rule.

43 + ∅ = 43
    A. 12; Subtraction Rule
    B. 0; Identity Property of Addition
    C. 0; Commutative Property of Addition
    D. 0; Associative Property of Addition
    Hint
  3.   Add mentally.

24 + 36 + 34

    A. 84 B. 98
    C. 104 D. 94
    Hint
  4.   Add mentally.

51 + 22 + 9
    A. 72 B. 81
    C. 82 D. 92
    Hint
  5.   When you subtract 0 from any number, the result is the number. Which addition rule is similar?
    A. Subtraction Rule B. Commutative Property of Addition
    C. Associative Property of Addition D. Identity Property of Addition
    Hint