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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 116 · 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. 1.406 + 179 =
  2. 2.481 − 181 =
  3. 3.199 + 277 =
  4. 4.738 − 117 =
  5. 5.223 + 493 =
  6. 6.584 + 551 =
  7. 7.813 − 211 =
  8. 8.711 + 612 =
  9. 9.385 + 267 =
  10. 10.387 + 349 =
  11. 11.478 + 585 =
  12. 12.532 − 353 =
  13. 13.838 − 402 =
  14. 14.681 + 144 =
  15. 15.435 + 334 =
  16. 16.906 − 447 =
  17. 17.832 − 261 =
  18. 18.478 − 169 =
  19. 19.769 − 119 =
  20. 20.416 + 191 =
  21. 21.567 + 461 =
  22. 22.329 + 396 =
  23. 23.442 − 162 =
  24. 24.835 − 734 =
  25. 25.668 + 457 =
  26. 26.232 + 593 =
  27. 27.243 + 493 =
  28. 28.523 − 289 =
  29. 29.730 − 408 =
  30. 30.380 + 466 =
  31. 31.262 + 364 =
  32. 32.868 − 639 =
  33. 33.517 + 281 =
  34. 34.579 − 217 =
  35. 35.177 + 139 =
  36. 36.380 + 346 =
  37. 37.642 − 467 =
  38. 38.448 + 373 =
  39. 39.675 + 449 =
  40. 40.289 + 361 =

Answer key

  1. 585
  2. 300
  3. 476
  4. 621
  5. 716
  6. 1135
  7. 602
  8. 1323
  9. 652
  10. 736
  11. 1063
  12. 179
  13. 436
  14. 825
  15. 769
  16. 459
  17. 571
  18. 309
  19. 650
  20. 607
  21. 1028
  22. 725
  23. 280
  24. 101
  25. 1125
  26. 825
  27. 736
  28. 234
  29. 322
  30. 846
  31. 626
  32. 229
  33. 798
  34. 362
  35. 316
  36. 726
  37. 175
  38. 821
  39. 1124
  40. 650

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