Fluently Add and Subtract Within 20 - 2nd Grade Math

1. What is the sum of $9 + 8$?

   $17$. Near doubles: $8 + 8 = 16$, so $9 + 8 = 17$.

2. What is the difference $12 - 4$?

   $8$. Half of 12 is 6, plus 2 more is 8.

3. What is $9 + 6$?

   $15$. Make 10: 9 + 1 = 10, then add 5 more.

4. What is $14 - 9$?

   $5$. Think: what plus 9 equals 14?

5. What is the sum of $3 + 9$?

   $12$. Make 10: $3 + 7 = 10$, then $10 + 2 = 12$.

6. What is the sum of $6 + 6$?

   $12$. Double 6 gives 12.

7. What is the missing addend in $9 + = 16$?

   $7$. Think: $9 + 7 = 16$, so the missing number is 7.

8. What is $12 - 6$?

   $6$. Half of 12 is 6.

9. What is the sum of $4 + 8$?

   $12$. Count up from 8: 9, 10, 11, 12.

10. What is the sum of $8 + 7$?

    $15$. Count up from 8: 9, 10, 11, 12, 13, 14, 15.

11. What is $19 - 10$?

    $9$. 19 minus 10 equals 9.

12. What is the difference $14 - 6$?

    $8$. Count back 6 from 14: 13, 12, 11, 10, 9, 8.

13. What is the difference $13 - 8$?

    $5$. Count back 8 from 13 or think $8 + 5 = 13$.

14. What is $16 - 8$?

    $8$. Half of 16 is 8.

15. What is the sum of $9 + 6$?

    $15$. Make 10 first: $9 + 1 = 10$, then $10 + 5 = 15$.

16. What is the sum of $9 + 7$?

    $16$. Think of it as $10 + 6 = 16$ since $9$ is close to $10$.

17. What is $3 + 8$?

    $11$. Make 10: 3 + 7 = 10, then add 1 more.

18. What is $15 - 7$?

    $8$. Count back 7 from 15 to get 8.

19. What is $8 + 8$?

    $16$. Double 8 equals 16.

20. What is the sum of $6 + 8$?

    $14$. Count on from 8: 9, 10, 11, 12, 13, 14.

21. What is $0 + 7$?

    $7$. Adding zero to any number gives the same number.

22. What is $18 - 9$?

    $9$. Half of 18 is 9.

23. What is $6 + 6$?

    $12$. Double 6 equals 12.

24. What is $9 + 9$?

    $18$. Double 9 equals 18.

25. What is the difference $16 - 9$?

    $7$. Think: What plus 9 equals 16? Count up from 9 to get 7.

26. What is the sum of $8 + 8$?

    $16$. Double 8 gives 16.

27. What is $11 - 4$?

    $7$. Count back 4 from 11 to get 7.

28. What is the missing number in $18 - = 9$?

    $9$. Think: $18 - 9 = 9$, so the missing number is 9.

29. What is the sum of $5 + 9$?

    $14$. Make 10: $5 + 5 = 10$, then $10 + 4 = 14$.

30. What is $7 + 8$?

    $15$. Think of 8 + 8 = 16, then subtract 1.

31. What is $20 - 6$?

    $14$. 20 minus 6 equals 14.

32. What is $9 + 0$?

    $9$. Zero plus any number equals that number.

33. What is $4 + 7$?

    $11$. Count up 7 from 4 to reach 11.

34. What is the sum of $7 + 7$?

    $14$. Double 7 gives 14.

35. What is $10 - 7$?

    $3$. Count back 7 from 10 to get 3.

36. What is $13 - 5$?

    $8$. 13 take away 5 leaves 8.

37. What is the difference $15 - 7$?

    $8$. Count back from 15: 14, 13, 12, 11, 10, 9, 8.

38. What is the missing addend in $6 + = 13$?

    $7$. Count up from 6 to 13: that's 7 jumps.

39. What is $5 + 9$?

    $14$. Make 10: 5 + 5 = 10, then add 4 more.

40. What is the sum of $9 + 9$?

    $18$. Double 9 gives 18.

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