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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 21 · 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. 1.886 − 523 =
  2. 2.531 + 191 =
  3. 3.882 − 414 =
  4. 4.591 + 157 =
  5. 5.299 + 221 =
  6. 6.200 + 346 =
  7. 7.194 + 661 =
  8. 8.554 − 282 =
  9. 9.812 − 388 =
  10. 10.574 − 133 =
  11. 11.202 + 187 =
  12. 12.359 + 141 =
  13. 13.684 − 196 =
  14. 14.499 + 402 =
  15. 15.632 − 236 =
  16. 16.365 + 153 =
  17. 17.239 + 602 =
  18. 18.312 + 161 =
  19. 19.772 − 309 =
  20. 20.474 + 621 =
  21. 21.434 − 183 =
  22. 22.759 − 121 =
  23. 23.497 − 316 =
  24. 24.499 − 282 =
  25. 25.376 + 185 =
  26. 26.480 − 249 =
  27. 27.646 + 551 =
  28. 28.612 − 222 =
  29. 29.316 + 141 =
  30. 30.471 + 431 =
  31. 31.790 − 244 =
  32. 32.548 + 583 =
  33. 33.677 − 377 =
  34. 34.656 − 176 =
  35. 35.748 − 357 =
  36. 36.623 − 481 =
  37. 37.910 − 216 =
  38. 38.594 + 485 =
  39. 39.670 + 298 =
  40. 40.210 + 412 =

Answer key

  1. 363
  2. 722
  3. 468
  4. 748
  5. 520
  6. 546
  7. 855
  8. 272
  9. 424
  10. 441
  11. 389
  12. 500
  13. 488
  14. 901
  15. 396
  16. 518
  17. 841
  18. 473
  19. 463
  20. 1095
  21. 251
  22. 638
  23. 181
  24. 217
  25. 561
  26. 231
  27. 1197
  28. 390
  29. 457
  30. 902
  31. 546
  32. 1131
  33. 300
  34. 480
  35. 391
  36. 142
  37. 694
  38. 1079
  39. 968
  40. 622

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