← Add and subtract 3-digit numbers left to right lesson New set →

3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 366 · 40 questions
TalentJR

How to do it in your head (Hundreds first): Keep the first number as it is and split the second into hundreds, tens and ones. Add (or take away) the hundreds first, then the tens. Finish with the ones — bridge through a ten if you need to.

NameDateTime takenScore ___ / 40
  1. 1.549 + 543 =
  2. 2.653 + 122 =
  3. 3.432 − 312 =
  4. 4.285 + 457 =
  5. 5.151 + 621 =
  6. 6.760 + 545 =
  7. 7.661 − 514 =
  8. 8.168 + 617 =
  9. 9.720 − 443 =
  10. 10.639 + 409 =
  11. 11.592 − 422 =
  12. 12.484 − 114 =
  13. 13.622 − 406 =
  14. 14.514 + 409 =
  15. 15.774 − 521 =
  16. 16.945 − 286 =
  17. 17.569 + 482 =
  18. 18.535 + 642 =
  19. 19.717 + 602 =
  20. 20.596 − 395 =
  21. 21.800 − 321 =
  22. 22.981 − 844 =
  23. 23.315 + 514 =
  24. 24.629 − 391 =
  25. 25.834 − 592 =
  26. 26.766 − 479 =
  27. 27.148 + 372 =
  28. 28.772 − 631 =
  29. 29.203 + 118 =
  30. 30.149 + 517 =
  31. 31.501 + 323 =
  32. 32.580 − 221 =
  33. 33.713 + 507 =
  34. 34.558 − 332 =
  35. 35.435 − 195 =
  36. 36.567 − 441 =
  37. 37.538 − 391 =
  38. 38.202 + 307 =
  39. 39.710 − 526 =
  40. 40.657 − 512 =

Answer key

  1. 1092
  2. 775
  3. 120
  4. 742
  5. 772
  6. 1305
  7. 147
  8. 785
  9. 277
  10. 1048
  11. 170
  12. 370
  13. 216
  14. 923
  15. 253
  16. 659
  17. 1051
  18. 1177
  19. 1319
  20. 201
  21. 479
  22. 137
  23. 829
  24. 238
  25. 242
  26. 287
  27. 520
  28. 141
  29. 321
  30. 666
  31. 824
  32. 359
  33. 1220
  34. 226
  35. 240
  36. 126
  37. 147
  38. 509
  39. 184
  40. 145

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