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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 384 · 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. 1.572 − 334 =
  2. 2.516 − 378 =
  3. 3.806 − 364 =
  4. 4.955 − 352 =
  5. 5.678 − 237 =
  6. 6.842 − 245 =
  7. 7.616 + 674 =
  8. 8.508 + 332 =
  9. 9.686 + 141 =
  10. 10.897 − 381 =
  11. 11.145 + 442 =
  12. 12.429 − 181 =
  13. 13.671 − 378 =
  14. 14.738 + 675 =
  15. 15.495 + 556 =
  16. 16.363 + 221 =
  17. 17.339 + 167 =
  18. 18.719 − 114 =
  19. 19.884 − 116 =
  20. 20.754 − 564 =
  21. 21.751 − 552 =
  22. 22.673 − 187 =
  23. 23.598 − 286 =
  24. 24.347 + 607 =
  25. 25.803 − 502 =
  26. 26.586 + 689 =
  27. 27.378 + 285 =
  28. 28.946 − 608 =
  29. 29.765 − 169 =
  30. 30.473 + 403 =
  31. 31.235 + 281 =
  32. 32.280 + 165 =
  33. 33.152 + 389 =
  34. 34.432 + 306 =
  35. 35.203 + 418 =
  36. 36.138 + 458 =
  37. 37.447 − 207 =
  38. 38.670 + 223 =
  39. 39.231 + 446 =
  40. 40.764 + 636 =

Answer key

  1. 238
  2. 138
  3. 442
  4. 603
  5. 441
  6. 597
  7. 1290
  8. 840
  9. 827
  10. 516
  11. 587
  12. 248
  13. 293
  14. 1413
  15. 1051
  16. 584
  17. 506
  18. 605
  19. 768
  20. 190
  21. 199
  22. 486
  23. 312
  24. 954
  25. 301
  26. 1275
  27. 663
  28. 338
  29. 596
  30. 876
  31. 516
  32. 445
  33. 541
  34. 738
  35. 621
  36. 596
  37. 240
  38. 893
  39. 677
  40. 1400

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