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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 598 · 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. 1.456 − 307 =
  2. 2.463 − 135 =
  3. 3.243 + 594 =
  4. 4.643 + 576 =
  5. 5.395 + 204 =
  6. 6.697 + 499 =
  7. 7.590 − 316 =
  8. 8.727 + 357 =
  9. 9.406 + 343 =
  10. 10.506 + 321 =
  11. 11.187 + 462 =
  12. 12.450 + 331 =
  13. 13.538 + 601 =
  14. 14.501 − 261 =
  15. 15.804 − 671 =
  16. 16.420 + 478 =
  17. 17.486 + 165 =
  18. 18.739 − 481 =
  19. 19.757 + 335 =
  20. 20.467 + 655 =
  21. 21.595 + 334 =
  22. 22.449 − 162 =
  23. 23.606 − 393 =
  24. 24.472 − 158 =
  25. 25.374 + 141 =
  26. 26.693 + 172 =
  27. 27.939 − 347 =
  28. 28.739 − 284 =
  29. 29.594 − 299 =
  30. 30.882 − 687 =
  31. 31.620 − 475 =
  32. 32.688 + 688 =
  33. 33.681 − 521 =
  34. 34.355 + 467 =
  35. 35.171 + 597 =
  36. 36.669 − 157 =
  37. 37.617 − 199 =
  38. 38.295 + 223 =
  39. 39.472 − 291 =
  40. 40.501 − 126 =

Answer key

  1. 149
  2. 328
  3. 837
  4. 1219
  5. 599
  6. 1196
  7. 274
  8. 1084
  9. 749
  10. 827
  11. 649
  12. 781
  13. 1139
  14. 240
  15. 133
  16. 898
  17. 651
  18. 258
  19. 1092
  20. 1122
  21. 929
  22. 287
  23. 213
  24. 314
  25. 515
  26. 865
  27. 592
  28. 455
  29. 295
  30. 195
  31. 145
  32. 1376
  33. 160
  34. 822
  35. 768
  36. 512
  37. 418
  38. 518
  39. 181
  40. 375

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