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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 872 · 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. 1.189 + 224 =
  2. 2.764 − 549 =
  3. 3.507 + 334 =
  4. 4.558 − 396 =
  5. 5.273 + 533 =
  6. 6.451 − 113 =
  7. 7.162 + 256 =
  8. 8.731 + 371 =
  9. 9.917 − 389 =
  10. 10.302 + 499 =
  11. 11.513 − 411 =
  12. 12.455 − 314 =
  13. 13.803 − 609 =
  14. 14.190 + 478 =
  15. 15.525 − 324 =
  16. 16.631 − 347 =
  17. 17.162 + 298 =
  18. 18.524 + 559 =
  19. 19.735 + 265 =
  20. 20.972 − 585 =
  21. 21.475 − 121 =
  22. 22.964 − 191 =
  23. 23.469 − 201 =
  24. 24.146 + 446 =
  25. 25.828 − 319 =
  26. 26.797 − 375 =
  27. 27.387 + 341 =
  28. 28.277 + 654 =
  29. 29.298 + 425 =
  30. 30.563 − 181 =
  31. 31.898 − 541 =
  32. 32.720 + 544 =
  33. 33.562 + 183 =
  34. 34.417 − 279 =
  35. 35.432 − 145 =
  36. 36.892 − 457 =
  37. 37.628 + 431 =
  38. 38.552 − 374 =
  39. 39.309 + 254 =
  40. 40.550 + 253 =

Answer key

  1. 413
  2. 215
  3. 841
  4. 162
  5. 806
  6. 338
  7. 418
  8. 1102
  9. 528
  10. 801
  11. 102
  12. 141
  13. 194
  14. 668
  15. 201
  16. 284
  17. 460
  18. 1083
  19. 1000
  20. 387
  21. 354
  22. 773
  23. 268
  24. 592
  25. 509
  26. 422
  27. 728
  28. 931
  29. 723
  30. 382
  31. 357
  32. 1264
  33. 745
  34. 138
  35. 287
  36. 435
  37. 1059
  38. 178
  39. 563
  40. 803

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