Add Within 100 - 1st Grade Math

1. What is the sum of $29 + 10$?

   $39$. Add tens: $20 + 10 = 30$, add ones: $9$, so $30 + 9 = 39$.

2. What is the sum of $65 + 20$?

   $85$. Add tens: $60 + 20 = 80$, add ones: $5$, so $80 + 5 = 85$.

3. What is the sum of $57 + 20$?

   $77$. Add tens: $50 + 20 = 70$, keep ones: $7$, so $77$.

4. What does it mean to "compose a ten" when adding within $100$?

   Trade $10$ ones for $1$ ten. When ones sum to $10$ or more, regroup as $1$ ten.

5. What is the sum of $76 + 10$?

   $86$. Add tens: $70 + 10 = 80$, add ones: $6$, so $80 + 6 = 86$.

6. What is the sum of $18 + 50$?

   $68$. Add tens: $10 + 50 = 60$, add ones: $8$, so $60 + 8 = 68$.

7. What is the sum of $69 + 4$?

   $73$. Add ones: $9 + 4 = 13$, compose a ten: $60 + 13 = 73$.

8. What is the sum of $84 + 5$?

   $89$. Add ones: $4 + 5 = 9$, keep tens: $80$, so $89$.

9. What is the sum of $73 + 10$?

   $83$. Add $10$ to the tens place: $70 + 10 = 80$, keep ones as $3$.

10. Identify the missing number: $52 + \square = 60$.

    $8$. Count up from $52$ to $60$: need $8$ more.

11. What is the sum of $19 + 7$?

    $26$. Add ones: $9 + 7 = 16$, regroup to get $26$.

12. What is the sum of $88 + 9$?

    $97$. Add ones: $8 + 9 = 17$, compose a ten: $80 + 17 = 97$.

13. Which place values do you add first in $2$-digit addition: tens or ones?

    Ones. Start with ones place to check if regrouping is needed.

14. What is the sum of $26 + 40$?

    $66$. Add tens: $20 + 40 = 60$, keep ones: $6$, so $66$.

15. Identify the missing number: $37 + 3 = \square$.

    $40$. Add ones: $7 + 3 = 10$, compose a ten: $30 + 10 = 40$.

16. What is the sum of $35 + 6$?

    $41$. Add ones: $5 + 6 = 11$, compose a ten: $30 + 11 = 41$.

17. What is the missing addend in $58 + \square = 65$?

    $7$. Find what adds to $8$ to make $15$ (ones become $5$, carry $1$).

18. What is the sum of $38 + 4$ using tens and ones?

    $42$. Add ones to ones: $8 + 4 = 12$, compose a ten to get $40 + 2$.

19. What is the sum of $41 + 30$?

    $71$. Add tens: $40 + 30 = 70$, keep ones: $1$, so $71$.

20. Identify the missing number: $\Box + 50 = 73$.

    $23$. Subtract: $73 - 50 = 23$ to find the missing number.

21. What is the sum of $34 + 5$?

    $39$. Add ones: $4 + 5 = 9$, keep tens: $30$, so $30 + 9 = 39$.

22. What is the sum of $62 + 30$ (add tens to tens)?

    $92$. Add tens to tens: $60 + 30 = 90$, keep ones as $2$.

23. What is the sum of $32 + 40$?

    $72$. Add tens: $30 + 40 = 70$, add ones: $2$, so $70 + 2 = 72$.

24. What is the sum of $37 + 6$?

    $43$. Add ones: $7 + 6 = 13$, regroup to get $43$.

25. Identify the missing number: $36 + \Box = 40$.

    $4$. Find what adds to $6$ to make $10$: it's $4$.

26. What is the missing addend in $36 + \square = 40$?

    $4$. Find what adds to $6$ to make $10$ (ones place).

27. What is the sum of $58 + 7$?

    $65$. Add ones: $8 + 7 = 15$, regroup to get $65$.

28. What is the sum of $67 + 9$?

    $76$. Add ones: $7 + 9 = 16$, regroup to get $76$.

29. What is the sum of $27 + 9$?

    $36$. Add ones: $7 + 9 = 16$, compose a ten: $20 + 16 = 36$.

30. What is the sum of $27 + 9$ (compose a ten if needed)?

    $36$. Add ones: $7 + 9 = 16$, compose a ten to get $30 + 6$.

31. What is the sum of $58 + 6$ (compose a ten if needed)?

    $64$. Add ones: $8 + 6 = 14$, compose a ten to get $60 + 4$.

32. What is the sum of $46 + 8$?

    $54$. Add ones: $6 + 8 = 14$, regroup to get $54$.

33. What is the sum of $62 + 8$?

    $70$. Add ones: $2 + 8 = 10$, regroup to get $70$.

34. What is the sum of $48 + 2$ (compose a ten)?

    $50$. Add ones: $8 + 2 = 10$, compose a ten to get $50$.

35. What is the sum of $45 + 20$ (add a multiple of $10$)?

    $65$. Add tens to tens: $40 + 20 = 60$, keep ones as $5$.

36. What is the sum of $39 + 1$ (compose a ten)?

    $40$. Add ones: $9 + 1 = 10$, compose a ten to get $40$.

37. What is the sum of $67 + 5$?

    $72$. Add ones to ones: $7 + 5 = 12$, compose a ten to get $70 + 2$.

38. What is the sum of $29 + 50$?

    $79$. Add tens to tens: $20 + 50 = 70$, keep ones as $9$.

39. What is the sum of $73 + 20$?

    $93$. Add tens: $70 + 20 = 90$, keep ones: $3$, so $93$.

40. What is the sum of $90 + 7$?

    $97$. Add ones: $0 + 7 = 7$, keep tens: $90$, so $97$.

41. What is the sum of $39 + 40$?

    $79$. Add tens: $30 + 40 = 70$, keep ones: $9$, so $79$.

42. What is the sum of $19 + 6$?

    $25$. Add ones: $9 + 6 = 15$, compose a ten: $10 + 15 = 25$.

43. What is the sum of $48 + 30$?

    $78$. Add tens: $40 + 30 = 70$, keep ones: $8$, so $78$.

44. What is the sum of $41 + 8$?

    $49$. Add ones to ones: $1 + 8 = 9$, keep tens as $40$.

45. What is the sum of $24 + 60$?

    $84$. Add tens to tens: $20 + 60 = 80$, keep ones as $4$.

46. What is the sum of $29 + 6$?

    $35$. Add ones: $9 + 6 = 15$, regroup to get $35$.

47. What is the sum of $55 + 10$?

    $65$. Add tens: $50 + 10 = 60$, keep ones: $5$, so $65$.

48. What is the sum of $46 + 7$?

    $53$. Add ones to ones: $6 + 7 = 13$, compose a ten to get $50 + 3$.

49. What is the sum of $19 + 8$ (compose a ten)?

    $27$. Add ones: $9 + 8 = 17$, compose a ten to get $20 + 7$.

50. What is the sum of $18 + 60$?

    $78$. Add tens: $10 + 60 = 70$, keep ones: $8$, so $78$.

51. What is the sum of $47 + 30$?

    $77$. Add tens: $40 + 30 = 70$, add ones: $7$, so $70 + 7 = 77$.

52. What is the sum of $55 + 9$ (compose a ten if needed)?

    $64$. Add ones: $5 + 9 = 14$, compose a ten to get $60 + 4$.

53. What is the sum of $48 + 3$?

    $51$. Add ones: $8 + 3 = 11$, compose a ten: $40 + 11 = 51$.

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