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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 826 · 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. 1.34 + 9 =
  2. 2.41 − 9 =
  3. 3.47 + 9 =
  4. 4.80 + 29 =
  5. 5.67 − 19 =
  6. 6.35 − 29 =
  7. 7.75 − 29 =
  8. 8.64 − 9 =
  9. 9.60 + 9 =
  10. 10.62 + 9 =
  11. 11.77 + 29 =
  12. 12.55 − 9 =
  13. 13.16 + 9 =
  14. 14.583 − 99 =
  15. 15.76 + 29 =
  16. 16.52 − 9 =
  17. 17.525 + 99 =
  18. 18.719 + 99 =
  19. 19.128 + 99 =
  20. 20.73 + 29 =
  21. 21.37 − 9 =
  22. 22.46 + 29 =
  23. 23.57 + 29 =
  24. 24.57 + 9 =
  25. 25.43 + 9 =
  26. 26.69 − 9 =
  27. 27.41 + 9 =
  28. 28.207 + 99 =
  29. 29.23 + 9 =
  30. 30.36 + 9 =
  31. 31.44 + 29 =
  32. 32.38 − 29 =
  33. 33.42 + 19 =
  34. 34.277 − 99 =
  35. 35.473 + 99 =
  36. 36.58 + 19 =
  37. 37.79 − 29 =
  38. 38.39 − 9 =
  39. 39.194 + 99 =
  40. 40.14 + 19 =

Answer key

  1. 43
  2. 32
  3. 56
  4. 109
  5. 48
  6. 6
  7. 46
  8. 55
  9. 69
  10. 71
  11. 106
  12. 46
  13. 25
  14. 484
  15. 105
  16. 43
  17. 624
  18. 818
  19. 227
  20. 102
  21. 28
  22. 75
  23. 86
  24. 66
  25. 52
  26. 60
  27. 50
  28. 306
  29. 32
  30. 45
  31. 73
  32. 9
  33. 61
  34. 178
  35. 572
  36. 77
  37. 50
  38. 30
  39. 293
  40. 33

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