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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 557 · 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. 1.144 + 652 =
  2. 2.551 − 185 =
  3. 3.838 − 533 =
  4. 4.786 − 642 =
  5. 5.471 + 566 =
  6. 6.487 + 548 =
  7. 7.890 − 181 =
  8. 8.414 − 181 =
  9. 9.539 − 393 =
  10. 10.336 + 309 =
  11. 11.741 + 144 =
  12. 12.347 + 264 =
  13. 13.611 − 466 =
  14. 14.205 + 478 =
  15. 15.751 + 261 =
  16. 16.669 − 362 =
  17. 17.624 + 339 =
  18. 18.401 + 251 =
  19. 19.615 + 228 =
  20. 20.485 − 126 =
  21. 21.255 + 411 =
  22. 22.497 − 315 =
  23. 23.516 + 467 =
  24. 24.880 − 611 =
  25. 25.679 + 259 =
  26. 26.557 + 517 =
  27. 27.683 + 646 =
  28. 28.196 + 187 =
  29. 29.700 − 559 =
  30. 30.900 − 187 =
  31. 31.727 − 124 =
  32. 32.178 + 368 =
  33. 33.506 − 352 =
  34. 34.706 − 418 =
  35. 35.582 + 255 =
  36. 36.630 + 294 =
  37. 37.501 + 337 =
  38. 38.950 − 245 =
  39. 39.551 − 172 =
  40. 40.650 + 368 =

Answer key

  1. 796
  2. 366
  3. 305
  4. 144
  5. 1037
  6. 1035
  7. 709
  8. 233
  9. 146
  10. 645
  11. 885
  12. 611
  13. 145
  14. 683
  15. 1012
  16. 307
  17. 963
  18. 652
  19. 843
  20. 359
  21. 666
  22. 182
  23. 983
  24. 269
  25. 938
  26. 1074
  27. 1329
  28. 383
  29. 141
  30. 713
  31. 603
  32. 546
  33. 154
  34. 288
  35. 837
  36. 924
  37. 838
  38. 705
  39. 379
  40. 1018

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