Math Games

Grade 3 - Number

Standard 3.N.10 - Use properties of addition to find the missing number of an equation.

Included Skills:

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.