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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 749 · 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. 1.26 + 19 =
  2. 2.698 + 99 =
  3. 3.46 − 19 =
  4. 4.55 + 19 =
  5. 5.75 − 29 =
  6. 6.69 + 9 =
  7. 7.34 − 29 =
  8. 8.773 + 99 =
  9. 9.52 + 9 =
  10. 10.22 − 19 =
  11. 11.63 + 29 =
  12. 12.68 + 9 =
  13. 13.210 + 99 =
  14. 14.48 − 29 =
  15. 15.23 + 29 =
  16. 16.179 + 99 =
  17. 17.73 + 29 =
  18. 18.519 − 99 =
  19. 19.27 − 19 =
  20. 20.413 + 99 =
  21. 21.23 + 9 =
  22. 22.22 − 9 =
  23. 23.27 − 9 =
  24. 24.51 + 29 =
  25. 25.38 − 9 =
  26. 26.54 + 9 =
  27. 27.551 − 99 =
  28. 28.198 + 99 =
  29. 29.15 + 29 =
  30. 30.79 + 29 =
  31. 31.250 − 99 =
  32. 32.45 + 9 =
  33. 33.89 − 29 =
  34. 34.26 − 9 =
  35. 35.47 + 9 =
  36. 36.40 − 9 =
  37. 37.41 + 9 =
  38. 38.93 − 29 =
  39. 39.41 − 9 =
  40. 40.28 + 19 =

Answer key

  1. 45
  2. 797
  3. 27
  4. 74
  5. 46
  6. 78
  7. 5
  8. 872
  9. 61
  10. 3
  11. 92
  12. 77
  13. 309
  14. 19
  15. 52
  16. 278
  17. 102
  18. 420
  19. 8
  20. 512
  21. 32
  22. 13
  23. 18
  24. 80
  25. 29
  26. 63
  27. 452
  28. 297
  29. 44
  30. 108
  31. 151
  32. 54
  33. 60
  34. 17
  35. 56
  36. 31
  37. 50
  38. 64
  39. 32
  40. 47

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