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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 641 · 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. 1.834 − 99 =
  2. 2.69 + 29 =
  3. 3.66 + 9 =
  4. 4.82 − 9 =
  5. 5.198 + 99 =
  6. 6.65 − 29 =
  7. 7.33 − 19 =
  8. 8.59 − 9 =
  9. 9.44 + 9 =
  10. 10.58 + 29 =
  11. 11.50 − 9 =
  12. 12.23 + 29 =
  13. 13.70 + 29 =
  14. 14.63 − 9 =
  15. 15.55 + 29 =
  16. 16.34 + 19 =
  17. 17.21 + 29 =
  18. 18.79 + 9 =
  19. 19.19 + 9 =
  20. 20.395 + 99 =
  21. 21.82 − 19 =
  22. 22.714 − 99 =
  23. 23.27 − 19 =
  24. 24.67 + 19 =
  25. 25.27 + 19 =
  26. 26.38 − 29 =
  27. 27.50 + 29 =
  28. 28.139 + 99 =
  29. 29.664 + 99 =
  30. 30.106 − 29 =
  31. 31.16 + 19 =
  32. 32.271 + 99 =
  33. 33.90 − 19 =
  34. 34.54 + 29 =
  35. 35.335 + 99 =
  36. 36.30 + 9 =
  37. 37.47 + 19 =
  38. 38.57 + 9 =
  39. 39.48 + 9 =
  40. 40.56 + 29 =

Answer key

  1. 735
  2. 98
  3. 75
  4. 73
  5. 297
  6. 36
  7. 14
  8. 50
  9. 53
  10. 87
  11. 41
  12. 52
  13. 99
  14. 54
  15. 84
  16. 53
  17. 50
  18. 88
  19. 28
  20. 494
  21. 63
  22. 615
  23. 8
  24. 86
  25. 46
  26. 9
  27. 79
  28. 238
  29. 763
  30. 77
  31. 35
  32. 370
  33. 71
  34. 83
  35. 434
  36. 39
  37. 66
  38. 66
  39. 57
  40. 85

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