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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 77 · 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. 1.678 − 551 =
  2. 2.273 + 315 =
  3. 3.759 + 471 =
  4. 4.179 + 563 =
  5. 5.926 − 582 =
  6. 6.857 − 613 =
  7. 7.981 − 544 =
  8. 8.798 − 472 =
  9. 9.652 + 244 =
  10. 10.562 − 229 =
  11. 11.506 − 236 =
  12. 12.775 − 554 =
  13. 13.433 − 162 =
  14. 14.603 + 264 =
  15. 15.528 − 156 =
  16. 16.637 + 258 =
  17. 17.211 + 132 =
  18. 18.657 − 443 =
  19. 19.384 + 202 =
  20. 20.554 − 386 =
  21. 21.537 − 289 =
  22. 22.601 − 193 =
  23. 23.304 + 381 =
  24. 24.840 − 628 =
  25. 25.672 − 474 =
  26. 26.350 + 641 =
  27. 27.725 − 296 =
  28. 28.175 + 446 =
  29. 29.448 − 295 =
  30. 30.710 + 673 =
  31. 31.676 − 471 =
  32. 32.529 − 344 =
  33. 33.876 − 667 =
  34. 34.558 + 556 =
  35. 35.546 − 114 =
  36. 36.272 + 339 =
  37. 37.298 + 592 =
  38. 38.543 + 382 =
  39. 39.505 + 287 =
  40. 40.634 − 156 =

Answer key

  1. 127
  2. 588
  3. 1230
  4. 742
  5. 344
  6. 244
  7. 437
  8. 326
  9. 896
  10. 333
  11. 270
  12. 221
  13. 271
  14. 867
  15. 372
  16. 895
  17. 343
  18. 214
  19. 586
  20. 168
  21. 248
  22. 408
  23. 685
  24. 212
  25. 198
  26. 991
  27. 429
  28. 621
  29. 153
  30. 1383
  31. 205
  32. 185
  33. 209
  34. 1114
  35. 432
  36. 611
  37. 890
  38. 925
  39. 792
  40. 478

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