Grade 3 - Number
Standard 3.N.10 - Use properties of addition to find the missing number of an equation.
Included Skills: Number Properties, Addition
Apply mental math strategies to determine addition facts and related subtraction facts to 18 (9 + 9). • Describe a mental mathematics strategy that could be used to determine a given basic fact, such as - doubles (e.g., for 6 + 8, think 7 + 7) - doubles plus one (e.g., for 6 + 7, think 6 + 6 + 1) - doubles take away one (e.g., for 6 + 7, think 7 + 7 – 1) - doubles plus two (e.g., for 6 + 8, think 6 + 6 + 2) - doubles take away two (e.g., for 6 + 8, think 8 + 8 – 2) - making 10 (e.g., for 6 + 8, think 6 + 4 + 4 or 8 + 2 + 4) - commutative property (e.g., for 3 + 9, think 9 + 3) - addition to subtraction (e.g., for 13 – 7, think 7 + o = 13) • Provide a rule for determining answers for adding and subtracting zero.