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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 332 · 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. 1.337 + 522 =
  2. 2.600 + 461 =
  3. 3.161 + 616 =
  4. 4.506 + 307 =
  5. 5.453 − 141 =
  6. 6.757 + 461 =
  7. 7.639 − 408 =
  8. 8.463 − 238 =
  9. 9.503 − 178 =
  10. 10.465 + 384 =
  11. 11.427 + 387 =
  12. 12.904 − 768 =
  13. 13.484 − 319 =
  14. 14.249 + 441 =
  15. 15.666 − 389 =
  16. 16.894 − 128 =
  17. 17.740 + 281 =
  18. 18.597 + 121 =
  19. 19.201 + 475 =
  20. 20.405 + 398 =
  21. 21.506 + 631 =
  22. 22.706 − 162 =
  23. 23.504 − 189 =
  24. 24.359 + 432 =
  25. 25.814 − 688 =
  26. 26.503 + 218 =
  27. 27.621 − 358 =
  28. 28.954 − 691 =
  29. 29.452 + 392 =
  30. 30.577 − 157 =
  31. 31.440 − 245 =
  32. 32.779 + 324 =
  33. 33.689 − 544 =
  34. 34.432 + 318 =
  35. 35.446 − 319 =
  36. 36.213 + 418 =
  37. 37.697 + 273 =
  38. 38.236 + 465 =
  39. 39.412 + 192 =
  40. 40.435 − 266 =

Answer key

  1. 859
  2. 1061
  3. 777
  4. 813
  5. 312
  6. 1218
  7. 231
  8. 225
  9. 325
  10. 849
  11. 814
  12. 136
  13. 165
  14. 690
  15. 277
  16. 766
  17. 1021
  18. 718
  19. 676
  20. 803
  21. 1137
  22. 544
  23. 315
  24. 791
  25. 126
  26. 721
  27. 263
  28. 263
  29. 844
  30. 420
  31. 195
  32. 1103
  33. 145
  34. 750
  35. 127
  36. 631
  37. 970
  38. 701
  39. 604
  40. 169

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