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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 11 · 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. 1.486 − 158 =
  2. 2.443 − 321 =
  3. 3.932 − 286 =
  4. 4.987 − 344 =
  5. 5.493 − 289 =
  6. 6.437 − 274 =
  7. 7.616 + 403 =
  8. 8.305 + 504 =
  9. 9.899 − 711 =
  10. 10.143 + 651 =
  11. 11.367 + 151 =
  12. 12.380 + 563 =
  13. 13.487 − 236 =
  14. 14.616 − 381 =
  15. 15.725 − 484 =
  16. 16.584 + 219 =
  17. 17.421 + 505 =
  18. 18.348 + 617 =
  19. 19.727 + 145 =
  20. 20.460 − 327 =
  21. 21.571 + 231 =
  22. 22.620 − 339 =
  23. 23.567 − 144 =
  24. 24.847 − 312 =
  25. 25.765 + 537 =
  26. 26.640 + 384 =
  27. 27.151 + 537 =
  28. 28.855 − 186 =
  29. 29.465 + 396 =
  30. 30.773 − 186 =
  31. 31.328 + 321 =
  32. 32.399 + 341 =
  33. 33.721 + 551 =
  34. 34.412 + 469 =
  35. 35.709 + 178 =
  36. 36.236 + 197 =
  37. 37.373 + 264 =
  38. 38.456 + 314 =
  39. 39.727 − 178 =
  40. 40.726 + 651 =

Answer key

  1. 328
  2. 122
  3. 646
  4. 643
  5. 204
  6. 163
  7. 1019
  8. 809
  9. 188
  10. 794
  11. 518
  12. 943
  13. 251
  14. 235
  15. 241
  16. 803
  17. 926
  18. 965
  19. 872
  20. 133
  21. 802
  22. 281
  23. 423
  24. 535
  25. 1302
  26. 1024
  27. 688
  28. 669
  29. 861
  30. 587
  31. 649
  32. 740
  33. 1272
  34. 881
  35. 887
  36. 433
  37. 637
  38. 770
  39. 549
  40. 1377

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