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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 576 · 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. 1.251 + 615 =
  2. 2.574 + 453 =
  3. 3.345 + 151 =
  4. 4.743 + 157 =
  5. 5.778 − 421 =
  6. 6.682 + 266 =
  7. 7.743 + 191 =
  8. 8.511 + 603 =
  9. 9.562 − 231 =
  10. 10.651 + 511 =
  11. 11.966 − 429 =
  12. 12.215 + 445 =
  13. 13.432 − 164 =
  14. 14.684 − 469 =
  15. 15.670 + 399 =
  16. 16.820 − 301 =
  17. 17.747 + 614 =
  18. 18.761 + 222 =
  19. 19.898 − 288 =
  20. 20.658 + 528 =
  21. 21.586 + 659 =
  22. 22.467 + 308 =
  23. 23.393 + 166 =
  24. 24.785 − 454 =
  25. 25.569 − 179 =
  26. 26.447 + 597 =
  27. 27.468 + 275 =
  28. 28.786 − 205 =
  29. 29.583 + 175 =
  30. 30.490 + 332 =
  31. 31.704 − 299 =
  32. 32.511 − 201 =
  33. 33.518 − 184 =
  34. 34.628 − 489 =
  35. 35.451 + 562 =
  36. 36.447 + 425 =
  37. 37.514 − 159 =
  38. 38.420 + 501 =
  39. 39.346 + 312 =
  40. 40.750 + 421 =

Answer key

  1. 866
  2. 1027
  3. 496
  4. 900
  5. 357
  6. 948
  7. 934
  8. 1114
  9. 331
  10. 1162
  11. 537
  12. 660
  13. 268
  14. 215
  15. 1069
  16. 519
  17. 1361
  18. 983
  19. 610
  20. 1186
  21. 1245
  22. 775
  23. 559
  24. 331
  25. 390
  26. 1044
  27. 743
  28. 581
  29. 758
  30. 822
  31. 405
  32. 310
  33. 334
  34. 139
  35. 1013
  36. 872
  37. 355
  38. 921
  39. 658
  40. 1171

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