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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 717 · 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. 1.432 + 458 =
  2. 2.184 + 201 =
  3. 3.932 − 507 =
  4. 4.373 + 469 =
  5. 5.714 − 165 =
  6. 6.848 − 397 =
  7. 7.176 + 327 =
  8. 8.162 + 248 =
  9. 9.296 + 144 =
  10. 10.313 + 252 =
  11. 11.507 − 201 =
  12. 12.809 − 369 =
  13. 13.840 − 592 =
  14. 14.532 + 194 =
  15. 15.926 − 194 =
  16. 16.530 + 687 =
  17. 17.812 − 159 =
  18. 18.692 − 294 =
  19. 19.641 − 488 =
  20. 20.648 + 463 =
  21. 21.887 − 753 =
  22. 22.676 − 257 =
  23. 23.744 + 261 =
  24. 24.601 + 115 =
  25. 25.361 + 319 =
  26. 26.482 − 279 =
  27. 27.633 − 397 =
  28. 28.793 − 204 =
  29. 29.511 − 246 =
  30. 30.271 + 113 =
  31. 31.591 + 426 =
  32. 32.953 − 466 =
  33. 33.533 − 151 =
  34. 34.430 + 428 =
  35. 35.729 − 277 =
  36. 36.947 − 271 =
  37. 37.612 − 341 =
  38. 38.496 + 273 =
  39. 39.688 − 354 =
  40. 40.368 + 413 =

Answer key

  1. 890
  2. 385
  3. 425
  4. 842
  5. 549
  6. 451
  7. 503
  8. 410
  9. 440
  10. 565
  11. 306
  12. 440
  13. 248
  14. 726
  15. 732
  16. 1217
  17. 653
  18. 398
  19. 153
  20. 1111
  21. 134
  22. 419
  23. 1005
  24. 716
  25. 680
  26. 203
  27. 236
  28. 589
  29. 265
  30. 384
  31. 1017
  32. 487
  33. 382
  34. 858
  35. 452
  36. 676
  37. 271
  38. 769
  39. 334
  40. 781

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