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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 354 · 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. 1.315 + 284 =
  2. 2.157 + 214 =
  3. 3.182 + 365 =
  4. 4.512 + 471 =
  5. 5.701 − 326 =
  6. 6.397 + 498 =
  7. 7.445 − 235 =
  8. 8.907 − 311 =
  9. 9.442 + 144 =
  10. 10.467 + 179 =
  11. 11.325 + 272 =
  12. 12.188 + 395 =
  13. 13.628 − 528 =
  14. 14.637 − 187 =
  15. 15.574 − 438 =
  16. 16.316 + 499 =
  17. 17.144 + 526 =
  18. 18.567 + 156 =
  19. 19.642 + 511 =
  20. 20.661 + 443 =
  21. 21.419 + 439 =
  22. 22.612 + 311 =
  23. 23.729 − 232 =
  24. 24.496 − 204 =
  25. 25.807 − 289 =
  26. 26.230 + 414 =
  27. 27.258 + 554 =
  28. 28.833 − 137 =
  29. 29.655 + 683 =
  30. 30.710 + 428 =
  31. 31.683 + 549 =
  32. 32.754 − 505 =
  33. 33.225 + 413 =
  34. 34.685 + 221 =
  35. 35.771 + 121 =
  36. 36.212 + 162 =
  37. 37.913 − 533 =
  38. 38.923 − 144 =
  39. 39.261 + 579 =
  40. 40.157 + 283 =

Answer key

  1. 599
  2. 371
  3. 547
  4. 983
  5. 375
  6. 895
  7. 210
  8. 596
  9. 586
  10. 646
  11. 597
  12. 583
  13. 100
  14. 450
  15. 136
  16. 815
  17. 670
  18. 723
  19. 1153
  20. 1104
  21. 858
  22. 923
  23. 497
  24. 292
  25. 518
  26. 644
  27. 812
  28. 696
  29. 1338
  30. 1138
  31. 1232
  32. 249
  33. 638
  34. 906
  35. 892
  36. 374
  37. 380
  38. 779
  39. 840
  40. 440

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