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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 141 · 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. 1.624 − 501 =
  2. 2.499 − 239 =
  3. 3.499 + 495 =
  4. 4.225 + 575 =
  5. 5.169 + 182 =
  6. 6.817 − 234 =
  7. 7.876 − 303 =
  8. 8.308 + 415 =
  9. 9.951 − 781 =
  10. 10.778 + 211 =
  11. 11.634 + 133 =
  12. 12.621 − 158 =
  13. 13.560 + 633 =
  14. 14.448 − 147 =
  15. 15.255 + 141 =
  16. 16.188 + 191 =
  17. 17.308 + 589 =
  18. 18.532 + 272 =
  19. 19.938 − 461 =
  20. 20.227 + 681 =
  21. 21.624 + 326 =
  22. 22.580 + 471 =
  23. 23.632 + 644 =
  24. 24.835 − 568 =
  25. 25.134 + 245 =
  26. 26.702 − 579 =
  27. 27.503 − 289 =
  28. 28.487 + 203 =
  29. 29.647 + 393 =
  30. 30.826 − 587 =
  31. 31.357 + 334 =
  32. 32.483 + 401 =
  33. 33.484 − 267 =
  34. 34.581 − 167 =
  35. 35.427 + 201 =
  36. 36.145 + 156 =
  37. 37.162 + 243 =
  38. 38.540 + 277 =
  39. 39.686 − 275 =
  40. 40.746 + 619 =

Answer key

  1. 123
  2. 260
  3. 994
  4. 800
  5. 351
  6. 583
  7. 573
  8. 723
  9. 170
  10. 989
  11. 767
  12. 463
  13. 1193
  14. 301
  15. 396
  16. 379
  17. 897
  18. 804
  19. 477
  20. 908
  21. 950
  22. 1051
  23. 1276
  24. 267
  25. 379
  26. 123
  27. 214
  28. 690
  29. 1040
  30. 239
  31. 691
  32. 884
  33. 217
  34. 414
  35. 628
  36. 301
  37. 405
  38. 817
  39. 411
  40. 1365

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