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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 684 · 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. 1.667 + 571 =
  2. 2.244 + 436 =
  3. 3.886 − 152 =
  4. 4.751 + 375 =
  5. 5.737 − 119 =
  6. 6.710 + 542 =
  7. 7.673 + 348 =
  8. 8.869 − 766 =
  9. 9.732 − 526 =
  10. 10.289 + 128 =
  11. 11.402 + 552 =
  12. 12.387 + 649 =
  13. 13.924 − 382 =
  14. 14.144 + 401 =
  15. 15.922 − 551 =
  16. 16.707 + 141 =
  17. 17.668 + 208 =
  18. 18.840 − 457 =
  19. 19.700 − 485 =
  20. 20.693 − 347 =
  21. 21.919 − 497 =
  22. 22.374 + 506 =
  23. 23.260 + 296 =
  24. 24.480 − 362 =
  25. 25.166 + 526 =
  26. 26.876 − 289 =
  27. 27.588 + 348 =
  28. 28.253 + 682 =
  29. 29.412 + 603 =
  30. 30.948 − 569 =
  31. 31.799 − 277 =
  32. 32.698 − 558 =
  33. 33.284 + 135 =
  34. 34.846 − 112 =
  35. 35.750 − 226 =
  36. 36.773 + 281 =
  37. 37.696 − 553 =
  38. 38.367 + 327 =
  39. 39.334 + 485 =
  40. 40.413 − 202 =

Answer key

  1. 1238
  2. 680
  3. 734
  4. 1126
  5. 618
  6. 1252
  7. 1021
  8. 103
  9. 206
  10. 417
  11. 954
  12. 1036
  13. 542
  14. 545
  15. 371
  16. 848
  17. 876
  18. 383
  19. 215
  20. 346
  21. 422
  22. 880
  23. 556
  24. 118
  25. 692
  26. 587
  27. 936
  28. 935
  29. 1015
  30. 379
  31. 522
  32. 140
  33. 419
  34. 734
  35. 524
  36. 1054
  37. 143
  38. 694
  39. 819
  40. 211

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