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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 213 · 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. 1.383 + 562 =
  2. 2.446 − 267 =
  3. 3.323 + 625 =
  4. 4.479 + 374 =
  5. 5.210 + 222 =
  6. 6.695 + 298 =
  7. 7.891 − 331 =
  8. 8.849 − 278 =
  9. 9.731 + 273 =
  10. 10.538 − 309 =
  11. 11.551 − 417 =
  12. 12.135 + 611 =
  13. 13.988 − 775 =
  14. 14.539 + 563 =
  15. 15.763 − 147 =
  16. 16.152 + 495 =
  17. 17.542 − 321 =
  18. 18.674 − 133 =
  19. 19.862 − 275 =
  20. 20.558 − 402 =
  21. 21.587 + 582 =
  22. 22.920 − 371 =
  23. 23.768 − 134 =
  24. 24.636 − 275 =
  25. 25.707 + 442 =
  26. 26.351 + 155 =
  27. 27.399 + 201 =
  28. 28.721 + 537 =
  29. 29.986 − 733 =
  30. 30.275 + 527 =
  31. 31.939 − 204 =
  32. 32.582 + 402 =
  33. 33.580 + 584 =
  34. 34.438 − 297 =
  35. 35.325 + 204 =
  36. 36.605 − 233 =
  37. 37.328 + 412 =
  38. 38.649 − 365 =
  39. 39.680 + 143 =
  40. 40.610 + 344 =

Answer key

  1. 945
  2. 179
  3. 948
  4. 853
  5. 432
  6. 993
  7. 560
  8. 571
  9. 1004
  10. 229
  11. 134
  12. 746
  13. 213
  14. 1102
  15. 616
  16. 647
  17. 221
  18. 541
  19. 587
  20. 156
  21. 1169
  22. 549
  23. 634
  24. 361
  25. 1149
  26. 506
  27. 600
  28. 1258
  29. 253
  30. 802
  31. 735
  32. 984
  33. 1164
  34. 141
  35. 529
  36. 372
  37. 740
  38. 284
  39. 823
  40. 954

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