Addition And Subtraction Fluency - 1st Grade Math

1. What is $12-8$ if you know the related fact $8+4=12$?

   $4$. Since $8+4=12$, the missing addend in $8+?=12$ is $4$.

2. What is the value of $11-7$ using the related addition fact $7+4=11$?

   $4$. Since $7+4=11$, then $11-7=4$.

3. What is $14-6$ by decomposing to ten: $14-4-2$?

   $8$. Subtract $4$ to reach $10$, then subtract remaining $2$.

4. What is $17-10$?

   $7$. Subtract $10$ from teen numbers by removing the ten.

5. What is the sum $8+6$ if you make a ten first?

   $14$. Break $8+6$ into $8+2+4$ to make $10+4$.

6. What is $10-6$?

   $4$. Basic subtraction fact within $10$.

7. What is the difference $14-5$ by decomposing to reach $10$ first?

   $9$. $14-4=10$, then $10-1=9$.

8. What strategy is shown by starting at $9$ and counting on $3$ more to find $9+3$?

   Counting on. Start at the larger number and count up by the smaller.

9. What is the sum $8+6$ using the making-ten strategy?

   $14$. $8+2=10$, then $10+4=14$.

10. What is $9-6$ if you know the related fact $6+3=9$?

    $3$. Since $6+3=9$, the missing addend in $6+?=9$ is $3$.

11. What is the sum $7+8$ by making ten first?

    $15$. $7+3=10$, then $10+5=15$.

12. What is the sum $6+7$ by using the easier sum $6+6+1$?

    $13$. Rewrite as $6+6+1$ since doubles are easier to recall.

13. What is $12-5$ by decomposing to ten: $12-2-3$?

    $7$. Subtract $2$ to reach $10$, then subtract remaining $3$.

14. What is the difference $16-7$ by decomposing to reach $10$ first?

    $9$. $16-6=10$, then $10-1=9$.

15. What strategy is shown by rewriting $8+6$ as $8+2+4$ to make $10$ first?

    Making ten. Breaks apart numbers to create $10$, then adds the rest.

16. What is the sum $3+8$ by counting on from $8$?

    $11$. Start at $8$ and count: $9, 10, 11$.

17. What is $6+6$?

    $12$. Doubles fact: $6$ added to itself.

18. What is the sum $4+9$ by counting on from $9$?

    $13$. Start at $9$ and count: $10, 11, 12, 13$.

19. What is $8+4$?

    $12$. Basic addition fact within $20$.

20. What is the difference $16-9$ by counting on from $9$ to $16$?

    $7$. Count up from $9$: $10, 11, 12, 13, 14, 15, 16$ is $7$ steps.

21. What is the value of $15-6$ using the fact that $6+9=15$?

    $9$. Since $6+9=15$, then $15-6=9$.

22. What is $9+5$ using making ten: $9+1+4$?

    $14$. Take $1$ from $5$ to make $10$ with $9$, then add remaining $4$.

23. What is the sum $10+7$ within $20$?

    $17$. Adding to $10$ is easy: just append the ones digit.

24. What is $11-3$ by decomposing to ten: $11-1-2$?

    $8$. Subtract $1$ to reach $10$, then subtract remaining $2$.

25. What is $12-4$ if you know the related fact $8+4=12$?

    $8$. Since $8+4=12$, the missing addend in $4+?=12$ is $8$.

26. What is $10-9$?

    $1$. Basic subtraction fact within $10$.

27. What is the sum $6+7$ by using an easier equivalent sum such as $6+6+1$?

    $13$. Rewrite as $6+6+1=12+1=13$.

28. What relationship helps you use $8+4=12$ to solve $12-8$ quickly?

    Addition and subtraction are inverse operations. Addition and subtraction undo each other.

29. What is the difference $20-10$?

    $10$. Subtracting $10$ from $20$ leaves $10$.

30. What is the difference $15-8$ by counting on from $8$ to $15$?

    $7$. Count up from $8$: $9, 10, 11, 12, 13, 14, 15$ is $7$ steps.

31. What is $7+7$?

    $14$. Doubles fact: $7$ added to itself.

32. What is the difference $13-4$ by decomposing to reach $10$ first?

    $9$. $13-3=10$, then $10-1=9$.

33. What strategy is shown by rewriting $13-4$ as $13-3-1$ to reach $10$ first?

    Decomposing to make ten. Breaks subtraction into steps that pass through $10$.

34. What is the difference $12-3$ by decomposing to reach $10$ first?

    $9$. $12-2=10$, then $10-1=9$.

35. What is the value of $12-8$ using the fact that $8+4=12$?

    $4$. Since $8+4=12$, then $12-8=4$.

36. What is $7+8$ using making ten: $7+3+5$?

    $15$. Take $3$ from $8$ to make $10$ with $7$, then add remaining $5$.

37. What is $10-7$ if you know the related fact $7+3=10$?

    $3$. Since $7+3=10$, the missing addend in $7+?=10$ is $3$.

38. What is the sum $9+9$ within $20$?

    $18$. Double facts: $9+9=18$.

39. What is $13-4$ by decomposing to ten: $13-3-1$?

    $9$. Subtract $3$ to reach $10$, then subtract remaining $1$.

40. What is the sum $9+5$ by making ten first?

    $14$. $9+1=10$, then $10+4=14$.

Study these flashcards