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

24 + ∅ = 18 + 24
    A. 18; Associative Property of Addition
    B. 18; Commutative Property of Addition
    C. 0; Identity Property of Addition
    D. 6; Subtraction Rule
    Hint
  2.   Add mentally.

18 + 41 + 12
    A. 61 B. 71
    C. 82 D. 81
    Hint
  3.   Add mentally.

32 + 18 + 40
    A. 80 B. 100
    C. 90 D. 70
    Hint
  4.   Add mentally.

51 + 22 + 9
    A. 82 B. 81
    C. 72 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. Associative Property of Addition
    C. Commutative Property of Addition D. Identity Property of Addition
    Hint