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Adding 9, 19 and 99 Mental Maths Worksheet

Mental maths lesson 4: Add and take away 9, 19 and 99 · Set 611 · 40 questions
TalentJR

How to do it in your head (Round and adjust): Add 9, 19, 99: add 10, 20, 100, then take 1 away. Take away 9, 19, 99: take away 10, 20, 100, then add 1 back. Ask yourself: did I use too much or too little?

NameDateTime takenScore ___ / 40
  1. 1.60 + 19 =
  2. 2.606 − 99 =
  3. 3.80 + 29 =
  4. 4.98 − 19 =
  5. 5.12 + 29 =
  6. 6.60 − 19 =
  7. 7.45 + 29 =
  8. 8.22 − 9 =
  9. 9.45 − 29 =
  10. 10.68 + 9 =
  11. 11.16 + 9 =
  12. 12.72 + 19 =
  13. 13.747 + 99 =
  14. 14.80 − 19 =
  15. 15.13 + 9 =
  16. 16.502 + 99 =
  17. 17.54 + 19 =
  18. 18.82 − 9 =
  19. 19.37 + 9 =
  20. 20.693 + 99 =
  21. 21.71 − 19 =
  22. 22.50 − 19 =
  23. 23.112 + 99 =
  24. 24.62 + 19 =
  25. 25.49 − 9 =
  26. 26.186 − 99 =
  27. 27.774 + 99 =
  28. 28.21 + 9 =
  29. 29.419 + 99 =
  30. 30.818 − 99 =
  31. 31.29 − 9 =
  32. 32.65 + 9 =
  33. 33.609 + 99 =
  34. 34.31 + 9 =
  35. 35.270 − 99 =
  36. 36.78 + 9 =
  37. 37.72 − 9 =
  38. 38.74 + 19 =
  39. 39.56 + 19 =
  40. 40.73 + 19 =

Answer key

  1. 79
  2. 507
  3. 109
  4. 79
  5. 41
  6. 41
  7. 74
  8. 13
  9. 16
  10. 77
  11. 25
  12. 91
  13. 846
  14. 61
  15. 22
  16. 601
  17. 73
  18. 73
  19. 46
  20. 792
  21. 52
  22. 31
  23. 211
  24. 81
  25. 40
  26. 87
  27. 873
  28. 30
  29. 518
  30. 719
  31. 20
  32. 74
  33. 708
  34. 40
  35. 171
  36. 87
  37. 63
  38. 93
  39. 75
  40. 92

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