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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 429 · 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. 1.977 − 598 =
  2. 2.901 − 366 =
  3. 3.469 − 368 =
  4. 4.203 + 482 =
  5. 5.455 − 229 =
  6. 6.527 + 537 =
  7. 7.509 − 329 =
  8. 8.632 − 513 =
  9. 9.391 + 568 =
  10. 10.906 − 669 =
  11. 11.940 − 506 =
  12. 12.696 + 219 =
  13. 13.463 − 166 =
  14. 14.772 + 201 =
  15. 15.267 + 147 =
  16. 16.726 + 396 =
  17. 17.757 + 303 =
  18. 18.263 + 216 =
  19. 19.708 − 461 =
  20. 20.255 + 197 =
  21. 21.589 + 531 =
  22. 22.575 − 367 =
  23. 23.406 + 161 =
  24. 24.461 + 303 =
  25. 25.702 + 638 =
  26. 26.476 − 251 =
  27. 27.305 + 253 =
  28. 28.843 − 336 =
  29. 29.577 + 599 =
  30. 30.319 + 262 =
  31. 31.767 + 492 =
  32. 32.332 + 118 =
  33. 33.570 + 401 =
  34. 34.692 − 561 =
  35. 35.783 − 617 =
  36. 36.257 + 672 =
  37. 37.386 + 667 =
  38. 38.474 − 239 =
  39. 39.931 − 418 =
  40. 40.136 + 543 =

Answer key

  1. 379
  2. 535
  3. 101
  4. 685
  5. 226
  6. 1064
  7. 180
  8. 119
  9. 959
  10. 237
  11. 434
  12. 915
  13. 297
  14. 973
  15. 414
  16. 1122
  17. 1060
  18. 479
  19. 247
  20. 452
  21. 1120
  22. 208
  23. 567
  24. 764
  25. 1340
  26. 225
  27. 558
  28. 507
  29. 1176
  30. 581
  31. 1259
  32. 450
  33. 971
  34. 131
  35. 166
  36. 929
  37. 1053
  38. 235
  39. 513
  40. 679

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