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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 147 · 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. 1.481 − 221 =
  2. 2.585 − 147 =
  3. 3.452 − 297 =
  4. 4.897 − 752 =
  5. 5.496 − 121 =
  6. 6.634 − 443 =
  7. 7.214 + 346 =
  8. 8.135 + 355 =
  9. 9.562 − 329 =
  10. 10.407 + 402 =
  11. 11.764 + 616 =
  12. 12.316 + 328 =
  13. 13.716 + 584 =
  14. 14.482 + 593 =
  15. 15.620 − 478 =
  16. 16.772 − 568 =
  17. 17.832 − 411 =
  18. 18.647 + 121 =
  19. 19.633 − 496 =
  20. 20.142 + 373 =
  21. 21.562 + 546 =
  22. 22.328 + 365 =
  23. 23.792 − 352 =
  24. 24.567 − 154 =
  25. 25.462 − 293 =
  26. 26.865 − 451 =
  27. 27.140 + 351 =
  28. 28.257 + 221 =
  29. 29.559 + 267 =
  30. 30.689 − 114 =
  31. 31.608 + 507 =
  32. 32.741 + 268 =
  33. 33.605 + 618 =
  34. 34.272 + 115 =
  35. 35.343 + 168 =
  36. 36.627 − 183 =
  37. 37.851 − 113 =
  38. 38.519 + 552 =
  39. 39.735 + 601 =
  40. 40.507 − 244 =

Answer key

  1. 260
  2. 438
  3. 155
  4. 145
  5. 375
  6. 191
  7. 560
  8. 490
  9. 233
  10. 809
  11. 1380
  12. 644
  13. 1300
  14. 1075
  15. 142
  16. 204
  17. 421
  18. 768
  19. 137
  20. 515
  21. 1108
  22. 693
  23. 440
  24. 413
  25. 169
  26. 414
  27. 491
  28. 478
  29. 826
  30. 575
  31. 1115
  32. 1009
  33. 1223
  34. 387
  35. 511
  36. 444
  37. 738
  38. 1071
  39. 1336
  40. 263

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