Mental strategies for addition and subtraction

Find the sum of 50 and 49.

• 100

• 97

• 109

• 99

If you have 310 apples and give away 11, how many do you have left?

• 299

• 300

• 289

• 100

What is the sum of 35 and 37?

• 70

• 71

• 72

• 73

What are the fact families for the numbers 6, 2, and 4?

• 4 + 2 = 6, 2 + 4 = 6, 6 - 4 = 2, 6 - 2 = 4

• 2 + 4 = 6, 6 - 4 = 2, 4 - 2 = 2

• 4 + 6 = 10, 10 - 4 = 6, 6 - 2 = 4

• 6 - 2 = 4, 2 - 6 = -4, 4 + 2 = 6

Which subtraction makes 24?

• 24 + 0

• 50 - 26

• 24 + 1 - 1

• 8 x 3

If you subtract 9 from 20, what is the result?

• 11

• 5

• 15

• 10

What is the sum of 3 + 8 + 2 + 8 using a "make 10" strategy?

• 20

• 22

• 21

• 23

What is the relationship between the numbers 5, 3, and 2 in subtraction?

• 2 - 3 = 5

• 3 + 2 = 5

• 5 - 3 = 2

• 3 - 5 = 2