← Add and take away 9, 19 and 99 lesson New set →

Adding 9, 19 and 99 Mental Maths Worksheet

Mental maths lesson 4: Add and take away 9, 19 and 99 · Set 58 · 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. 1.672 + 99 =
  2. 2.17 + 29 =
  3. 3.29 − 9 =
  4. 4.62 + 19 =
  5. 5.66 − 9 =
  6. 6.52 + 29 =
  7. 7.695 + 99 =
  8. 8.57 + 9 =
  9. 9.50 − 19 =
  10. 10.668 + 99 =
  11. 11.56 + 9 =
  12. 12.77 + 29 =
  13. 13.29 + 19 =
  14. 14.33 − 19 =
  15. 15.45 − 9 =
  16. 16.45 − 19 =
  17. 17.48 + 29 =
  18. 18.28 − 19 =
  19. 19.55 − 29 =
  20. 20.286 − 99 =
  21. 21.73 + 19 =
  22. 22.35 + 29 =
  23. 23.67 + 9 =
  24. 24.12 + 19 =
  25. 25.30 − 19 =
  26. 26.32 − 29 =
  27. 27.734 + 99 =
  28. 28.67 − 9 =
  29. 29.53 + 9 =
  30. 30.63 + 9 =
  31. 31.359 − 99 =
  32. 32.35 + 19 =
  33. 33.36 − 29 =
  34. 34.72 + 19 =
  35. 35.247 − 99 =
  36. 36.73 + 29 =
  37. 37.12 + 9 =
  38. 38.85 − 19 =
  39. 39.48 − 29 =
  40. 40.34 − 29 =

Answer key

  1. 771
  2. 46
  3. 20
  4. 81
  5. 57
  6. 81
  7. 794
  8. 66
  9. 31
  10. 767
  11. 65
  12. 106
  13. 48
  14. 14
  15. 36
  16. 26
  17. 77
  18. 9
  19. 26
  20. 187
  21. 92
  22. 64
  23. 76
  24. 31
  25. 11
  26. 3
  27. 833
  28. 58
  29. 62
  30. 72
  31. 260
  32. 54
  33. 7
  34. 91
  35. 148
  36. 102
  37. 21
  38. 66
  39. 19
  40. 5

Free mental maths lessons, practice and worksheets at talentjr.in/mental-maths