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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 843 · 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. 1.161 + 362 =
  2. 2.770 − 384 =
  3. 3.785 + 464 =
  4. 4.551 + 207 =
  5. 5.826 − 363 =
  6. 6.348 + 121 =
  7. 7.779 + 178 =
  8. 8.539 − 169 =
  9. 9.787 − 629 =
  10. 10.311 + 236 =
  11. 11.649 + 581 =
  12. 12.865 − 705 =
  13. 13.780 + 369 =
  14. 14.920 − 349 =
  15. 15.316 + 538 =
  16. 16.604 − 329 =
  17. 17.733 + 551 =
  18. 18.837 − 166 =
  19. 19.871 − 568 =
  20. 20.458 + 532 =
  21. 21.237 + 267 =
  22. 22.837 − 733 =
  23. 23.908 − 418 =
  24. 24.502 − 165 =
  25. 25.475 − 173 =
  26. 26.179 + 466 =
  27. 27.484 − 338 =
  28. 28.275 + 504 =
  29. 29.617 + 422 =
  30. 30.808 − 548 =
  31. 31.843 − 359 =
  32. 32.643 − 463 =
  33. 33.228 + 388 =
  34. 34.789 + 254 =
  35. 35.845 − 524 =
  36. 36.374 + 188 =
  37. 37.422 − 301 =
  38. 38.684 + 178 =
  39. 39.246 + 119 =
  40. 40.791 − 662 =

Answer key

  1. 523
  2. 386
  3. 1249
  4. 758
  5. 463
  6. 469
  7. 957
  8. 370
  9. 158
  10. 547
  11. 1230
  12. 160
  13. 1149
  14. 571
  15. 854
  16. 275
  17. 1284
  18. 671
  19. 303
  20. 990
  21. 504
  22. 104
  23. 490
  24. 337
  25. 302
  26. 645
  27. 146
  28. 779
  29. 1039
  30. 260
  31. 484
  32. 180
  33. 616
  34. 1043
  35. 321
  36. 562
  37. 121
  38. 862
  39. 365
  40. 129

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