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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 191 · 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. 1.870 − 266 =
  2. 2.449 + 621 =
  3. 3.616 − 452 =
  4. 4.547 + 253 =
  5. 5.139 + 632 =
  6. 6.549 − 168 =
  7. 7.136 + 151 =
  8. 8.928 − 587 =
  9. 9.794 − 575 =
  10. 10.491 − 149 =
  11. 11.771 − 391 =
  12. 12.585 + 497 =
  13. 13.581 − 319 =
  14. 14.214 + 253 =
  15. 15.899 − 223 =
  16. 16.783 + 553 =
  17. 17.470 − 183 =
  18. 18.598 − 483 =
  19. 19.808 − 236 =
  20. 20.701 + 661 =
  21. 21.768 − 265 =
  22. 22.223 + 388 =
  23. 23.846 − 204 =
  24. 24.443 + 532 =
  25. 25.345 + 151 =
  26. 26.743 − 231 =
  27. 27.467 + 417 =
  28. 28.200 + 183 =
  29. 29.445 − 345 =
  30. 30.575 − 353 =
  31. 31.430 + 588 =
  32. 32.599 − 117 =
  33. 33.199 + 169 =
  34. 34.541 + 135 =
  35. 35.905 − 389 =
  36. 36.554 + 241 =
  37. 37.786 + 546 =
  38. 38.247 + 541 =
  39. 39.178 + 415 =
  40. 40.565 − 371 =

Answer key

  1. 604
  2. 1070
  3. 164
  4. 800
  5. 771
  6. 381
  7. 287
  8. 341
  9. 219
  10. 342
  11. 380
  12. 1082
  13. 262
  14. 467
  15. 676
  16. 1336
  17. 287
  18. 115
  19. 572
  20. 1362
  21. 503
  22. 611
  23. 642
  24. 975
  25. 496
  26. 512
  27. 884
  28. 383
  29. 100
  30. 222
  31. 1018
  32. 482
  33. 368
  34. 676
  35. 516
  36. 795
  37. 1332
  38. 788
  39. 593
  40. 194

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