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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 895 · 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. 1.76 + 19 =
  2. 2.75 − 19 =
  3. 3.64 − 29 =
  4. 4.76 + 9 =
  5. 5.40 − 19 =
  6. 6.23 + 9 =
  7. 7.79 − 9 =
  8. 8.819 − 99 =
  9. 9.367 − 99 =
  10. 10.26 − 9 =
  11. 11.580 − 99 =
  12. 12.50 + 9 =
  13. 13.88 − 19 =
  14. 14.37 − 9 =
  15. 15.48 + 29 =
  16. 16.283 + 99 =
  17. 17.78 + 19 =
  18. 18.34 − 29 =
  19. 19.98 − 19 =
  20. 20.37 − 29 =
  21. 21.17 − 9 =
  22. 22.70 + 9 =
  23. 23.20 + 9 =
  24. 24.23 + 29 =
  25. 25.80 + 19 =
  26. 26.49 + 9 =
  27. 27.42 − 29 =
  28. 28.41 + 9 =
  29. 29.28 + 19 =
  30. 30.21 + 29 =
  31. 31.29 − 19 =
  32. 32.60 + 29 =
  33. 33.37 − 19 =
  34. 34.397 + 99 =
  35. 35.69 − 29 =
  36. 36.18 + 19 =
  37. 37.66 + 29 =
  38. 38.591 − 99 =
  39. 39.381 + 99 =
  40. 40.36 − 9 =

Answer key

  1. 95
  2. 56
  3. 35
  4. 85
  5. 21
  6. 32
  7. 70
  8. 720
  9. 268
  10. 17
  11. 481
  12. 59
  13. 69
  14. 28
  15. 77
  16. 382
  17. 97
  18. 5
  19. 79
  20. 8
  21. 8
  22. 79
  23. 29
  24. 52
  25. 99
  26. 58
  27. 13
  28. 50
  29. 47
  30. 50
  31. 10
  32. 89
  33. 18
  34. 496
  35. 40
  36. 37
  37. 95
  38. 492
  39. 480
  40. 27

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