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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 979 · 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. 1.745 − 381 =
  2. 2.633 + 399 =
  3. 3.198 + 224 =
  4. 4.358 + 244 =
  5. 5.482 − 137 =
  6. 6.742 + 151 =
  7. 7.611 − 497 =
  8. 8.745 + 391 =
  9. 9.874 − 494 =
  10. 10.204 + 144 =
  11. 11.388 + 191 =
  12. 12.767 − 163 =
  13. 13.406 + 164 =
  14. 14.957 − 814 =
  15. 15.644 + 519 =
  16. 16.336 + 421 =
  17. 17.129 + 151 =
  18. 18.713 + 148 =
  19. 19.494 − 256 =
  20. 20.565 + 509 =
  21. 21.755 − 275 =
  22. 22.678 − 247 =
  23. 23.449 − 126 =
  24. 24.247 + 141 =
  25. 25.659 + 147 =
  26. 26.375 + 139 =
  27. 27.606 + 206 =
  28. 28.522 − 132 =
  29. 29.490 + 611 =
  30. 30.568 − 421 =
  31. 31.594 − 191 =
  32. 32.270 + 271 =
  33. 33.347 + 228 =
  34. 34.591 − 471 =
  35. 35.188 + 686 =
  36. 36.361 + 266 =
  37. 37.743 − 203 =
  38. 38.256 + 688 =
  39. 39.645 − 332 =
  40. 40.136 + 303 =

Answer key

  1. 364
  2. 1032
  3. 422
  4. 602
  5. 345
  6. 893
  7. 114
  8. 1136
  9. 380
  10. 348
  11. 579
  12. 604
  13. 570
  14. 143
  15. 1163
  16. 757
  17. 280
  18. 861
  19. 238
  20. 1074
  21. 480
  22. 431
  23. 323
  24. 388
  25. 806
  26. 514
  27. 812
  28. 390
  29. 1101
  30. 147
  31. 403
  32. 541
  33. 575
  34. 120
  35. 874
  36. 627
  37. 540
  38. 944
  39. 313
  40. 439

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