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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 33 · 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. 1.344 + 267 =
  2. 2.575 + 251 =
  3. 3.603 − 501 =
  4. 4.708 + 255 =
  5. 5.950 − 828 =
  6. 6.604 + 362 =
  7. 7.806 − 148 =
  8. 8.880 − 606 =
  9. 9.457 − 309 =
  10. 10.479 + 115 =
  11. 11.847 − 467 =
  12. 12.814 − 346 =
  13. 13.719 − 613 =
  14. 14.152 + 295 =
  15. 15.313 + 233 =
  16. 16.461 + 279 =
  17. 17.851 − 433 =
  18. 18.639 − 148 =
  19. 19.811 − 576 =
  20. 20.927 − 217 =
  21. 21.625 + 499 =
  22. 22.164 + 317 =
  23. 23.564 − 181 =
  24. 24.687 + 261 =
  25. 25.555 + 551 =
  26. 26.435 + 489 =
  27. 27.372 + 571 =
  28. 28.587 + 617 =
  29. 29.187 + 651 =
  30. 30.458 + 341 =
  31. 31.767 − 117 =
  32. 32.327 + 669 =
  33. 33.698 + 619 =
  34. 34.690 − 519 =
  35. 35.410 + 379 =
  36. 36.435 + 551 =
  37. 37.656 + 571 =
  38. 38.910 − 252 =
  39. 39.706 + 271 =
  40. 40.854 − 508 =

Answer key

  1. 611
  2. 826
  3. 102
  4. 963
  5. 122
  6. 966
  7. 658
  8. 274
  9. 148
  10. 594
  11. 380
  12. 468
  13. 106
  14. 447
  15. 546
  16. 740
  17. 418
  18. 491
  19. 235
  20. 710
  21. 1124
  22. 481
  23. 383
  24. 948
  25. 1106
  26. 924
  27. 943
  28. 1204
  29. 838
  30. 799
  31. 650
  32. 996
  33. 1317
  34. 171
  35. 789
  36. 986
  37. 1227
  38. 658
  39. 977
  40. 346

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