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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 838 · 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. 1.19 + 9 =
  2. 2.24 − 19 =
  3. 3.29 + 19 =
  4. 4.78 − 29 =
  5. 5.43 − 19 =
  6. 6.54 + 19 =
  7. 7.83 − 9 =
  8. 8.34 − 29 =
  9. 9.24 − 9 =
  10. 10.99 − 19 =
  11. 11.77 + 19 =
  12. 12.57 − 9 =
  13. 13.60 − 9 =
  14. 14.247 − 99 =
  15. 15.95 − 29 =
  16. 16.672 + 99 =
  17. 17.41 − 29 =
  18. 18.20 + 9 =
  19. 19.54 − 9 =
  20. 20.635 + 99 =
  21. 21.71 + 29 =
  22. 22.60 + 9 =
  23. 23.17 + 19 =
  24. 24.788 + 99 =
  25. 25.16 + 9 =
  26. 26.16 + 29 =
  27. 27.55 − 29 =
  28. 28.91 − 29 =
  29. 29.374 + 99 =
  30. 30.420 + 99 =
  31. 31.48 − 9 =
  32. 32.73 + 19 =
  33. 33.46 + 29 =
  34. 34.56 − 19 =
  35. 35.70 + 19 =
  36. 36.74 − 29 =
  37. 37.40 + 9 =
  38. 38.322 + 99 =
  39. 39.37 − 19 =
  40. 40.52 − 9 =

Answer key

  1. 28
  2. 5
  3. 48
  4. 49
  5. 24
  6. 73
  7. 74
  8. 5
  9. 15
  10. 80
  11. 96
  12. 48
  13. 51
  14. 148
  15. 66
  16. 771
  17. 12
  18. 29
  19. 45
  20. 734
  21. 100
  22. 69
  23. 36
  24. 887
  25. 25
  26. 45
  27. 26
  28. 62
  29. 473
  30. 519
  31. 39
  32. 92
  33. 75
  34. 37
  35. 89
  36. 45
  37. 49
  38. 421
  39. 18
  40. 43

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