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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 880 · 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. 1.488 + 174 =
  2. 2.695 + 394 =
  3. 3.182 + 281 =
  4. 4.943 − 578 =
  5. 5.204 + 499 =
  6. 6.250 + 323 =
  7. 7.614 − 287 =
  8. 8.977 − 494 =
  9. 9.840 − 721 =
  10. 10.276 + 235 =
  11. 11.176 + 471 =
  12. 12.252 + 246 =
  13. 13.127 + 365 =
  14. 14.533 − 316 =
  15. 15.678 + 171 =
  16. 16.430 − 154 =
  17. 17.779 + 608 =
  18. 18.327 + 201 =
  19. 19.655 − 413 =
  20. 20.749 + 628 =
  21. 21.269 + 277 =
  22. 22.783 + 592 =
  23. 23.614 + 145 =
  24. 24.694 + 145 =
  25. 25.331 + 627 =
  26. 26.718 + 582 =
  27. 27.464 − 178 =
  28. 28.405 + 378 =
  29. 29.981 − 511 =
  30. 30.603 − 173 =
  31. 31.468 − 336 =
  32. 32.159 + 131 =
  33. 33.372 + 621 =
  34. 34.583 − 183 =
  35. 35.143 + 415 =
  36. 36.395 + 471 =
  37. 37.978 − 204 =
  38. 38.676 − 181 =
  39. 39.881 − 615 =
  40. 40.511 + 513 =

Answer key

  1. 662
  2. 1089
  3. 463
  4. 365
  5. 703
  6. 573
  7. 327
  8. 483
  9. 119
  10. 511
  11. 647
  12. 498
  13. 492
  14. 217
  15. 849
  16. 276
  17. 1387
  18. 528
  19. 242
  20. 1377
  21. 546
  22. 1375
  23. 759
  24. 839
  25. 958
  26. 1300
  27. 286
  28. 783
  29. 470
  30. 430
  31. 132
  32. 290
  33. 993
  34. 400
  35. 558
  36. 866
  37. 774
  38. 495
  39. 266
  40. 1024

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