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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 877 · 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. 1.667 − 129 =
  2. 2.564 − 341 =
  3. 3.713 − 535 =
  4. 4.301 + 559 =
  5. 5.496 − 321 =
  6. 6.953 − 591 =
  7. 7.564 − 181 =
  8. 8.125 + 675 =
  9. 9.231 + 389 =
  10. 10.577 − 371 =
  11. 11.713 − 495 =
  12. 12.464 + 632 =
  13. 13.417 − 299 =
  14. 14.549 − 336 =
  15. 15.499 + 341 =
  16. 16.423 + 333 =
  17. 17.563 − 146 =
  18. 18.638 + 516 =
  19. 19.766 − 275 =
  20. 20.648 + 135 =
  21. 21.606 − 366 =
  22. 22.499 − 125 =
  23. 23.458 − 344 =
  24. 24.763 + 591 =
  25. 25.943 − 814 =
  26. 26.776 − 454 =
  27. 27.461 − 241 =
  28. 28.315 + 321 =
  29. 29.717 + 487 =
  30. 30.368 + 251 =
  31. 31.793 − 128 =
  32. 32.682 − 165 =
  33. 33.544 + 491 =
  34. 34.438 − 255 =
  35. 35.638 − 402 =
  36. 36.496 − 312 =
  37. 37.131 + 183 =
  38. 38.585 − 433 =
  39. 39.492 + 684 =
  40. 40.431 − 157 =

Answer key

  1. 538
  2. 223
  3. 178
  4. 860
  5. 175
  6. 362
  7. 383
  8. 800
  9. 620
  10. 206
  11. 218
  12. 1096
  13. 118
  14. 213
  15. 840
  16. 756
  17. 417
  18. 1154
  19. 491
  20. 783
  21. 240
  22. 374
  23. 114
  24. 1354
  25. 129
  26. 322
  27. 220
  28. 636
  29. 1204
  30. 619
  31. 665
  32. 517
  33. 1035
  34. 183
  35. 236
  36. 184
  37. 314
  38. 152
  39. 1176
  40. 274

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