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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 83 · 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. 1.563 − 329 =
  2. 2.810 − 541 =
  3. 3.497 + 348 =
  4. 4.603 + 271 =
  5. 5.221 + 245 =
  6. 6.911 − 252 =
  7. 7.987 − 591 =
  8. 8.654 − 149 =
  9. 9.214 + 421 =
  10. 10.966 − 283 =
  11. 11.977 − 352 =
  12. 12.143 + 651 =
  13. 13.651 − 486 =
  14. 14.357 + 238 =
  15. 15.260 + 381 =
  16. 16.139 + 283 =
  17. 17.423 + 317 =
  18. 18.587 + 362 =
  19. 19.155 + 283 =
  20. 20.422 − 126 =
  21. 21.433 − 257 =
  22. 22.139 + 528 =
  23. 23.548 + 128 =
  24. 24.547 − 302 =
  25. 25.466 + 159 =
  26. 26.558 + 131 =
  27. 27.885 − 471 =
  28. 28.519 + 271 =
  29. 29.449 − 307 =
  30. 30.194 + 605 =
  31. 31.205 + 485 =
  32. 32.164 + 271 =
  33. 33.527 + 262 =
  34. 34.633 + 625 =
  35. 35.508 + 556 =
  36. 36.148 + 534 =
  37. 37.512 − 273 =
  38. 38.765 − 498 =
  39. 39.475 + 249 =
  40. 40.891 − 471 =

Answer key

  1. 234
  2. 269
  3. 845
  4. 874
  5. 466
  6. 659
  7. 396
  8. 505
  9. 635
  10. 683
  11. 625
  12. 794
  13. 165
  14. 595
  15. 641
  16. 422
  17. 740
  18. 949
  19. 438
  20. 296
  21. 176
  22. 667
  23. 676
  24. 245
  25. 625
  26. 689
  27. 414
  28. 790
  29. 142
  30. 799
  31. 690
  32. 435
  33. 789
  34. 1258
  35. 1064
  36. 682
  37. 239
  38. 267
  39. 724
  40. 420

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