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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 588 · 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. 1.768 + 385 =
  2. 2.291 + 461 =
  3. 3.732 + 375 =
  4. 4.833 − 471 =
  5. 5.898 − 167 =
  6. 6.464 + 633 =
  7. 7.435 + 572 =
  8. 8.695 − 485 =
  9. 9.848 − 248 =
  10. 10.581 − 194 =
  11. 11.143 + 352 =
  12. 12.926 − 731 =
  13. 13.355 + 505 =
  14. 14.442 + 173 =
  15. 15.755 − 266 =
  16. 16.463 − 121 =
  17. 17.267 + 159 =
  18. 18.652 − 211 =
  19. 19.476 − 132 =
  20. 20.475 − 144 =
  21. 21.398 + 268 =
  22. 22.853 − 297 =
  23. 23.703 − 399 =
  24. 24.540 + 116 =
  25. 25.767 − 531 =
  26. 26.744 + 563 =
  27. 27.482 − 191 =
  28. 28.294 + 343 =
  29. 29.623 − 224 =
  30. 30.459 − 291 =
  31. 31.814 − 415 =
  32. 32.437 + 233 =
  33. 33.437 − 217 =
  34. 34.311 + 201 =
  35. 35.409 + 524 =
  36. 36.338 + 219 =
  37. 37.175 + 348 =
  38. 38.682 − 541 =
  39. 39.330 + 498 =
  40. 40.246 + 113 =

Answer key

  1. 1153
  2. 752
  3. 1107
  4. 362
  5. 731
  6. 1097
  7. 1007
  8. 210
  9. 600
  10. 387
  11. 495
  12. 195
  13. 860
  14. 615
  15. 489
  16. 342
  17. 426
  18. 441
  19. 344
  20. 331
  21. 666
  22. 556
  23. 304
  24. 656
  25. 236
  26. 1307
  27. 291
  28. 637
  29. 399
  30. 168
  31. 399
  32. 670
  33. 220
  34. 512
  35. 933
  36. 557
  37. 523
  38. 141
  39. 828
  40. 359

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