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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 779 · 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. 1.135 + 231 =
  2. 2.342 + 297 =
  3. 3.247 + 483 =
  4. 4.398 + 689 =
  5. 5.582 − 216 =
  6. 6.469 + 348 =
  7. 7.800 − 122 =
  8. 8.558 + 305 =
  9. 9.210 + 442 =
  10. 10.706 − 541 =
  11. 11.308 + 318 =
  12. 12.977 − 227 =
  13. 13.789 + 201 =
  14. 14.680 − 501 =
  15. 15.424 + 597 =
  16. 16.334 + 657 =
  17. 17.610 − 238 =
  18. 18.467 + 351 =
  19. 19.929 − 534 =
  20. 20.676 + 362 =
  21. 21.218 + 116 =
  22. 22.330 + 212 =
  23. 23.699 + 631 =
  24. 24.755 + 195 =
  25. 25.227 + 464 =
  26. 26.848 − 251 =
  27. 27.147 + 618 =
  28. 28.457 + 444 =
  29. 29.433 + 613 =
  30. 30.478 − 257 =
  31. 31.493 − 245 =
  32. 32.180 + 501 =
  33. 33.544 − 263 =
  34. 34.723 + 492 =
  35. 35.891 − 521 =
  36. 36.194 + 279 =
  37. 37.375 + 201 =
  38. 38.571 − 252 =
  39. 39.335 + 264 =
  40. 40.188 + 607 =

Answer key

  1. 366
  2. 639
  3. 730
  4. 1087
  5. 366
  6. 817
  7. 678
  8. 863
  9. 652
  10. 165
  11. 626
  12. 750
  13. 990
  14. 179
  15. 1021
  16. 991
  17. 372
  18. 818
  19. 395
  20. 1038
  21. 334
  22. 542
  23. 1330
  24. 950
  25. 691
  26. 597
  27. 765
  28. 901
  29. 1046
  30. 221
  31. 248
  32. 681
  33. 281
  34. 1215
  35. 370
  36. 473
  37. 576
  38. 319
  39. 599
  40. 795

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