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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 689 · 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. 1.958 − 758 =
  2. 2.463 − 154 =
  3. 3.546 − 269 =
  4. 4.323 + 602 =
  5. 5.623 − 467 =
  6. 6.420 − 193 =
  7. 7.523 − 144 =
  8. 8.668 − 528 =
  9. 9.731 − 316 =
  10. 10.148 + 323 =
  11. 11.415 + 525 =
  12. 12.895 − 784 =
  13. 13.570 − 341 =
  14. 14.783 + 389 =
  15. 15.414 − 231 =
  16. 16.260 + 275 =
  17. 17.780 − 476 =
  18. 18.671 − 383 =
  19. 19.545 + 503 =
  20. 20.440 + 631 =
  21. 21.768 − 566 =
  22. 22.733 + 341 =
  23. 23.544 + 129 =
  24. 24.692 + 376 =
  25. 25.573 + 241 =
  26. 26.604 − 411 =
  27. 27.135 + 457 =
  28. 28.989 − 148 =
  29. 29.631 − 401 =
  30. 30.389 + 259 =
  31. 31.371 + 121 =
  32. 32.177 + 226 =
  33. 33.690 + 418 =
  34. 34.810 − 158 =
  35. 35.560 − 258 =
  36. 36.133 + 206 =
  37. 37.398 + 351 =
  38. 38.186 + 156 =
  39. 39.404 + 344 =
  40. 40.309 + 608 =

Answer key

  1. 200
  2. 309
  3. 277
  4. 925
  5. 156
  6. 227
  7. 379
  8. 140
  9. 415
  10. 471
  11. 940
  12. 111
  13. 229
  14. 1172
  15. 183
  16. 535
  17. 304
  18. 288
  19. 1048
  20. 1071
  21. 202
  22. 1074
  23. 673
  24. 1068
  25. 814
  26. 193
  27. 592
  28. 841
  29. 230
  30. 648
  31. 492
  32. 403
  33. 1108
  34. 652
  35. 302
  36. 339
  37. 749
  38. 342
  39. 748
  40. 917

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