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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 127 · 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. 1.22 + 19 =
  2. 2.38 − 19 =
  3. 3.30 − 19 =
  4. 4.80 + 9 =
  5. 5.16 + 9 =
  6. 6.34 − 9 =
  7. 7.60 + 29 =
  8. 8.37 − 19 =
  9. 9.64 − 9 =
  10. 10.15 + 19 =
  11. 11.58 + 9 =
  12. 12.67 + 19 =
  13. 13.304 − 99 =
  14. 14.227 + 99 =
  15. 15.39 + 29 =
  16. 16.56 + 29 =
  17. 17.42 − 19 =
  18. 18.70 + 9 =
  19. 19.295 − 99 =
  20. 20.28 − 19 =
  21. 21.24 + 9 =
  22. 22.52 − 29 =
  23. 23.23 − 9 =
  24. 24.152 − 99 =
  25. 25.300 − 99 =
  26. 26.56 + 19 =
  27. 27.55 − 9 =
  28. 28.32 − 9 =
  29. 29.66 + 9 =
  30. 30.459 − 99 =
  31. 31.40 − 19 =
  32. 32.27 − 9 =
  33. 33.27 − 19 =
  34. 34.17 + 29 =
  35. 35.81 − 9 =
  36. 36.68 − 9 =
  37. 37.86 − 9 =
  38. 38.253 − 99 =
  39. 39.50 − 9 =
  40. 40.47 − 9 =

Answer key

  1. 41
  2. 19
  3. 11
  4. 89
  5. 25
  6. 25
  7. 89
  8. 18
  9. 55
  10. 34
  11. 67
  12. 86
  13. 205
  14. 326
  15. 68
  16. 85
  17. 23
  18. 79
  19. 196
  20. 9
  21. 33
  22. 23
  23. 14
  24. 53
  25. 201
  26. 75
  27. 46
  28. 23
  29. 75
  30. 360
  31. 21
  32. 18
  33. 8
  34. 46
  35. 72
  36. 59
  37. 77
  38. 154
  39. 41
  40. 38

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