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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 741 · 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. 1.68 + 19 =
  2. 2.61 + 29 =
  3. 3.47 + 19 =
  4. 4.35 + 9 =
  5. 5.699 + 99 =
  6. 6.160 − 99 =
  7. 7.12 + 29 =
  8. 8.27 − 19 =
  9. 9.653 − 99 =
  10. 10.98 − 29 =
  11. 11.21 + 19 =
  12. 12.317 − 99 =
  13. 13.150 + 99 =
  14. 14.64 + 19 =
  15. 15.308 + 99 =
  16. 16.82 − 19 =
  17. 17.64 − 29 =
  18. 18.54 + 29 =
  19. 19.50 + 19 =
  20. 20.88 − 19 =
  21. 21.63 + 29 =
  22. 22.21 + 9 =
  23. 23.73 − 19 =
  24. 24.326 − 99 =
  25. 25.33 − 19 =
  26. 26.87 − 29 =
  27. 27.51 − 29 =
  28. 28.22 − 19 =
  29. 29.142 + 99 =
  30. 30.27 − 9 =
  31. 31.26 + 29 =
  32. 32.344 − 99 =
  33. 33.57 − 9 =
  34. 34.21 + 29 =
  35. 35.464 − 99 =
  36. 36.36 + 29 =
  37. 37.18 + 19 =
  38. 38.335 − 99 =
  39. 39.25 + 19 =
  40. 40.384 − 99 =

Answer key

  1. 87
  2. 90
  3. 66
  4. 44
  5. 798
  6. 61
  7. 41
  8. 8
  9. 554
  10. 69
  11. 40
  12. 218
  13. 249
  14. 83
  15. 407
  16. 63
  17. 35
  18. 83
  19. 69
  20. 69
  21. 92
  22. 30
  23. 54
  24. 227
  25. 14
  26. 58
  27. 22
  28. 3
  29. 241
  30. 18
  31. 55
  32. 245
  33. 48
  34. 50
  35. 365
  36. 65
  37. 37
  38. 236
  39. 44
  40. 285

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