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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 607 · 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. 1.511 + 357 =
  2. 2.701 + 291 =
  3. 3.578 + 198 =
  4. 4.428 − 281 =
  5. 5.170 + 225 =
  6. 6.459 − 343 =
  7. 7.508 − 204 =
  8. 8.757 + 591 =
  9. 9.735 + 349 =
  10. 10.785 + 168 =
  11. 11.969 − 477 =
  12. 12.498 − 335 =
  13. 13.368 + 601 =
  14. 14.777 + 436 =
  15. 15.320 + 544 =
  16. 16.352 + 459 =
  17. 17.516 − 243 =
  18. 18.175 + 652 =
  19. 19.663 − 114 =
  20. 20.549 − 169 =
  21. 21.609 − 236 =
  22. 22.676 + 351 =
  23. 23.198 + 204 =
  24. 24.817 − 355 =
  25. 25.331 + 268 =
  26. 26.287 + 551 =
  27. 27.855 − 284 =
  28. 28.542 − 414 =
  29. 29.414 − 262 =
  30. 30.486 + 494 =
  31. 31.600 − 351 =
  32. 32.509 + 476 =
  33. 33.197 + 117 =
  34. 34.335 + 663 =
  35. 35.744 − 329 =
  36. 36.430 + 641 =
  37. 37.881 − 237 =
  38. 38.419 − 311 =
  39. 39.519 − 304 =
  40. 40.691 + 391 =

Answer key

  1. 868
  2. 992
  3. 776
  4. 147
  5. 395
  6. 116
  7. 304
  8. 1348
  9. 1084
  10. 953
  11. 492
  12. 163
  13. 969
  14. 1213
  15. 864
  16. 811
  17. 273
  18. 827
  19. 549
  20. 380
  21. 373
  22. 1027
  23. 402
  24. 462
  25. 599
  26. 838
  27. 571
  28. 128
  29. 152
  30. 980
  31. 249
  32. 985
  33. 314
  34. 998
  35. 415
  36. 1071
  37. 644
  38. 108
  39. 215
  40. 1082

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