← 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 602 · 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 + 9 =
  2. 2.241 − 99 =
  3. 3.579 − 99 =
  4. 4.34 − 29 =
  5. 5.476 + 99 =
  6. 6.66 + 9 =
  7. 7.271 + 99 =
  8. 8.13 + 9 =
  9. 9.59 − 29 =
  10. 10.449 − 99 =
  11. 11.19 + 9 =
  12. 12.13 + 29 =
  13. 13.36 − 29 =
  14. 14.33 − 19 =
  15. 15.72 − 9 =
  16. 16.88 − 19 =
  17. 17.62 − 19 =
  18. 18.157 + 99 =
  19. 19.42 − 29 =
  20. 20.586 − 99 =
  21. 21.51 + 9 =
  22. 22.14 + 29 =
  23. 23.23 + 19 =
  24. 24.17 − 9 =
  25. 25.251 + 99 =
  26. 26.75 + 9 =
  27. 27.15 + 9 =
  28. 28.72 + 19 =
  29. 29.354 + 99 =
  30. 30.67 − 19 =
  31. 31.46 − 19 =
  32. 32.38 − 9 =
  33. 33.54 − 29 =
  34. 34.23 − 19 =
  35. 35.23 + 9 =
  36. 36.29 + 9 =
  37. 37.187 + 99 =
  38. 38.54 + 9 =
  39. 39.97 − 29 =
  40. 40.582 + 99 =

Answer key

  1. 31
  2. 142
  3. 480
  4. 5
  5. 575
  6. 75
  7. 370
  8. 22
  9. 30
  10. 350
  11. 28
  12. 42
  13. 7
  14. 14
  15. 63
  16. 69
  17. 43
  18. 256
  19. 13
  20. 487
  21. 60
  22. 43
  23. 42
  24. 8
  25. 350
  26. 84
  27. 24
  28. 91
  29. 453
  30. 48
  31. 27
  32. 29
  33. 25
  34. 4
  35. 32
  36. 38
  37. 286
  38. 63
  39. 68
  40. 681

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