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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 144 · 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. 1.554 + 99 =
  2. 2.27 + 19 =
  3. 3.18 + 29 =
  4. 4.22 + 9 =
  5. 5.75 + 9 =
  6. 6.96 − 29 =
  7. 7.20 − 9 =
  8. 8.69 + 29 =
  9. 9.48 + 29 =
  10. 10.327 + 99 =
  11. 11.76 + 19 =
  12. 12.21 + 29 =
  13. 13.56 − 29 =
  14. 14.58 + 29 =
  15. 15.60 − 19 =
  16. 16.31 + 19 =
  17. 17.33 − 19 =
  18. 18.588 + 99 =
  19. 19.462 + 99 =
  20. 20.64 + 9 =
  21. 21.54 + 29 =
  22. 22.27 + 9 =
  23. 23.58 − 19 =
  24. 24.522 − 99 =
  25. 25.51 + 9 =
  26. 26.47 + 9 =
  27. 27.62 − 29 =
  28. 28.55 − 9 =
  29. 29.826 − 99 =
  30. 30.55 + 29 =
  31. 31.730 − 99 =
  32. 32.18 − 9 =
  33. 33.63 − 29 =
  34. 34.68 − 9 =
  35. 35.825 − 99 =
  36. 36.32 + 19 =
  37. 37.72 − 9 =
  38. 38.345 − 99 =
  39. 39.107 − 29 =
  40. 40.33 + 9 =

Answer key

  1. 653
  2. 46
  3. 47
  4. 31
  5. 84
  6. 67
  7. 11
  8. 98
  9. 77
  10. 426
  11. 95
  12. 50
  13. 27
  14. 87
  15. 41
  16. 50
  17. 14
  18. 687
  19. 561
  20. 73
  21. 83
  22. 36
  23. 39
  24. 423
  25. 60
  26. 56
  27. 33
  28. 46
  29. 727
  30. 84
  31. 631
  32. 9
  33. 34
  34. 59
  35. 726
  36. 51
  37. 63
  38. 246
  39. 78
  40. 42

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