← 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 847 · 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. 1.15 + 9 =
  2. 2.607 + 99 =
  3. 3.55 + 9 =
  4. 4.38 − 19 =
  5. 5.65 + 9 =
  6. 6.43 − 9 =
  7. 7.175 − 99 =
  8. 8.63 − 19 =
  9. 9.32 − 29 =
  10. 10.509 + 99 =
  11. 11.16 + 19 =
  12. 12.26 + 19 =
  13. 13.35 − 29 =
  14. 14.449 − 99 =
  15. 15.18 + 9 =
  16. 16.66 + 19 =
  17. 17.14 + 29 =
  18. 18.420 − 99 =
  19. 19.80 + 29 =
  20. 20.78 + 19 =
  21. 21.51 − 9 =
  22. 22.48 + 9 =
  23. 23.24 − 19 =
  24. 24.40 + 9 =
  25. 25.13 + 29 =
  26. 26.67 − 9 =
  27. 27.49 + 29 =
  28. 28.63 − 9 =
  29. 29.336 − 99 =
  30. 30.72 − 9 =
  31. 31.78 + 29 =
  32. 32.126 + 99 =
  33. 33.104 − 29 =
  34. 34.551 + 99 =
  35. 35.34 − 9 =
  36. 36.110 + 99 =
  37. 37.53 + 9 =
  38. 38.22 − 9 =
  39. 39.28 − 19 =
  40. 40.338 − 99 =

Answer key

  1. 24
  2. 706
  3. 64
  4. 19
  5. 74
  6. 34
  7. 76
  8. 44
  9. 3
  10. 608
  11. 35
  12. 45
  13. 6
  14. 350
  15. 27
  16. 85
  17. 43
  18. 321
  19. 109
  20. 97
  21. 42
  22. 57
  23. 5
  24. 49
  25. 42
  26. 58
  27. 78
  28. 54
  29. 237
  30. 63
  31. 107
  32. 225
  33. 75
  34. 650
  35. 25
  36. 209
  37. 62
  38. 13
  39. 9
  40. 239

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