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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 762 · 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. 1.207 + 222 =
  2. 2.487 − 266 =
  3. 3.589 − 201 =
  4. 4.133 + 134 =
  5. 5.223 + 621 =
  6. 6.651 + 332 =
  7. 7.217 + 503 =
  8. 8.788 − 561 =
  9. 9.421 − 202 =
  10. 10.424 + 132 =
  11. 11.429 + 241 =
  12. 12.591 − 291 =
  13. 13.814 − 281 =
  14. 14.671 + 496 =
  15. 15.316 + 636 =
  16. 16.501 − 184 =
  17. 17.666 + 654 =
  18. 18.449 + 462 =
  19. 19.873 − 491 =
  20. 20.591 − 411 =
  21. 21.829 − 316 =
  22. 22.453 − 345 =
  23. 23.644 − 512 =
  24. 24.951 − 771 =
  25. 25.398 + 588 =
  26. 26.288 + 501 =
  27. 27.663 + 616 =
  28. 28.727 + 176 =
  29. 29.619 − 171 =
  30. 30.625 − 134 =
  31. 31.668 + 241 =
  32. 32.603 − 145 =
  33. 33.736 + 465 =
  34. 34.731 − 405 =
  35. 35.495 − 132 =
  36. 36.206 + 442 =
  37. 37.549 + 332 =
  38. 38.412 + 658 =
  39. 39.194 + 231 =
  40. 40.709 + 654 =

Answer key

  1. 429
  2. 221
  3. 388
  4. 267
  5. 844
  6. 983
  7. 720
  8. 227
  9. 219
  10. 556
  11. 670
  12. 300
  13. 533
  14. 1167
  15. 952
  16. 317
  17. 1320
  18. 911
  19. 382
  20. 180
  21. 513
  22. 108
  23. 132
  24. 180
  25. 986
  26. 789
  27. 1279
  28. 903
  29. 448
  30. 491
  31. 909
  32. 458
  33. 1201
  34. 326
  35. 363
  36. 648
  37. 881
  38. 1070
  39. 425
  40. 1363

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