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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 340 · 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. 1.546 − 311 =
  2. 2.871 − 153 =
  3. 3.613 − 371 =
  4. 4.841 − 225 =
  5. 5.719 + 514 =
  6. 6.272 + 376 =
  7. 7.540 − 321 =
  8. 8.167 + 507 =
  9. 9.672 + 262 =
  10. 10.757 − 484 =
  11. 11.726 + 571 =
  12. 12.597 + 166 =
  13. 13.239 + 347 =
  14. 14.610 − 263 =
  15. 15.542 − 243 =
  16. 16.892 − 415 =
  17. 17.506 − 131 =
  18. 18.694 + 121 =
  19. 19.572 − 134 =
  20. 20.619 + 411 =
  21. 21.214 + 214 =
  22. 22.338 + 348 =
  23. 23.677 − 496 =
  24. 24.549 + 451 =
  25. 25.286 + 613 =
  26. 26.234 + 649 =
  27. 27.494 + 431 =
  28. 28.507 − 249 =
  29. 29.294 + 318 =
  30. 30.318 + 576 =
  31. 31.471 − 228 =
  32. 32.486 − 281 =
  33. 33.562 + 367 =
  34. 34.743 − 366 =
  35. 35.585 − 175 =
  36. 36.382 + 281 =
  37. 37.324 + 307 =
  38. 38.304 + 142 =
  39. 39.598 − 169 =
  40. 40.587 − 191 =

Answer key

  1. 235
  2. 718
  3. 242
  4. 616
  5. 1233
  6. 648
  7. 219
  8. 674
  9. 934
  10. 273
  11. 1297
  12. 763
  13. 586
  14. 347
  15. 299
  16. 477
  17. 375
  18. 815
  19. 438
  20. 1030
  21. 428
  22. 686
  23. 181
  24. 1000
  25. 899
  26. 883
  27. 925
  28. 258
  29. 612
  30. 894
  31. 243
  32. 205
  33. 929
  34. 377
  35. 410
  36. 663
  37. 631
  38. 446
  39. 429
  40. 396

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