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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 7 · 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. 1.46 + 9 =
  2. 2.98 − 29 =
  3. 3.52 + 9 =
  4. 4.30 + 19 =
  5. 5.46 + 19 =
  6. 6.58 + 29 =
  7. 7.50 − 29 =
  8. 8.366 − 99 =
  9. 9.19 + 29 =
  10. 10.17 + 9 =
  11. 11.356 + 99 =
  12. 12.60 + 29 =
  13. 13.381 − 99 =
  14. 14.86 − 9 =
  15. 15.461 + 99 =
  16. 16.23 + 19 =
  17. 17.77 − 19 =
  18. 18.37 − 9 =
  19. 19.61 + 19 =
  20. 20.23 − 9 =
  21. 21.25 − 19 =
  22. 22.388 − 99 =
  23. 23.30 − 9 =
  24. 24.50 + 9 =
  25. 25.420 + 99 =
  26. 26.41 − 9 =
  27. 27.66 + 29 =
  28. 28.80 − 9 =
  29. 29.35 + 29 =
  30. 30.16 + 19 =
  31. 31.46 − 9 =
  32. 32.33 + 29 =
  33. 33.464 + 99 =
  34. 34.261 + 99 =
  35. 35.19 + 19 =
  36. 36.875 − 99 =
  37. 37.157 + 99 =
  38. 38.22 + 29 =
  39. 39.59 + 19 =
  40. 40.716 + 99 =

Answer key

  1. 55
  2. 69
  3. 61
  4. 49
  5. 65
  6. 87
  7. 21
  8. 267
  9. 48
  10. 26
  11. 455
  12. 89
  13. 282
  14. 77
  15. 560
  16. 42
  17. 58
  18. 28
  19. 80
  20. 14
  21. 6
  22. 289
  23. 21
  24. 59
  25. 519
  26. 32
  27. 95
  28. 71
  29. 64
  30. 35
  31. 37
  32. 62
  33. 563
  34. 360
  35. 38
  36. 776
  37. 256
  38. 51
  39. 78
  40. 815

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