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3-Digit Mental Addition and Subtraction Worksheet

Mental maths lesson 20: Add and subtract 3-digit numbers left to right · Set 208 · 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. 1.881 − 412 =
  2. 2.487 − 135 =
  3. 3.505 + 144 =
  4. 4.662 − 121 =
  5. 5.861 − 467 =
  6. 6.140 + 482 =
  7. 7.293 + 236 =
  8. 8.564 − 462 =
  9. 9.360 + 117 =
  10. 10.505 + 402 =
  11. 11.799 − 274 =
  12. 12.292 + 119 =
  13. 13.712 − 527 =
  14. 14.546 − 445 =
  15. 15.290 + 511 =
  16. 16.618 − 329 =
  17. 17.514 + 259 =
  18. 18.984 − 659 =
  19. 19.320 + 385 =
  20. 20.652 + 399 =
  21. 21.589 + 343 =
  22. 22.491 + 364 =
  23. 23.931 − 474 =
  24. 24.936 − 834 =
  25. 25.337 + 238 =
  26. 26.966 − 125 =
  27. 27.177 + 521 =
  28. 28.670 + 636 =
  29. 29.216 + 411 =
  30. 30.357 + 211 =
  31. 31.302 + 247 =
  32. 32.518 + 658 =
  33. 33.623 + 477 =
  34. 34.651 + 225 =
  35. 35.743 + 122 =
  36. 36.171 + 244 =
  37. 37.501 − 371 =
  38. 38.846 − 703 =
  39. 39.216 + 514 =
  40. 40.907 − 259 =

Answer key

  1. 469
  2. 352
  3. 649
  4. 541
  5. 394
  6. 622
  7. 529
  8. 102
  9. 477
  10. 907
  11. 525
  12. 411
  13. 185
  14. 101
  15. 801
  16. 289
  17. 773
  18. 325
  19. 705
  20. 1051
  21. 932
  22. 855
  23. 457
  24. 102
  25. 575
  26. 841
  27. 698
  28. 1306
  29. 627
  30. 568
  31. 549
  32. 1176
  33. 1100
  34. 876
  35. 865
  36. 415
  37. 130
  38. 143
  39. 730
  40. 648

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