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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 129 · 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. 1.887 − 723 =
  2. 2.193 + 194 =
  3. 3.469 − 301 =
  4. 4.587 − 299 =
  5. 5.965 − 525 =
  6. 6.674 + 257 =
  7. 7.955 − 155 =
  8. 8.683 + 677 =
  9. 9.175 + 636 =
  10. 10.607 + 233 =
  11. 11.472 + 646 =
  12. 12.600 + 267 =
  13. 13.437 + 405 =
  14. 14.513 − 321 =
  15. 15.561 + 326 =
  16. 16.511 − 131 =
  17. 17.560 − 114 =
  18. 18.681 − 577 =
  19. 19.854 − 459 =
  20. 20.614 − 179 =
  21. 21.976 − 375 =
  22. 22.670 − 458 =
  23. 23.643 + 488 =
  24. 24.270 + 561 =
  25. 25.528 − 221 =
  26. 26.128 + 378 =
  27. 27.715 − 531 =
  28. 28.204 + 574 =
  29. 29.651 − 137 =
  30. 30.252 + 419 =
  31. 31.599 + 112 =
  32. 32.742 − 349 =
  33. 33.723 − 202 =
  34. 34.975 − 549 =
  35. 35.256 + 176 =
  36. 36.175 + 288 =
  37. 37.432 + 222 =
  38. 38.629 + 484 =
  39. 39.201 + 603 =
  40. 40.192 + 121 =

Answer key

  1. 164
  2. 387
  3. 168
  4. 288
  5. 440
  6. 931
  7. 800
  8. 1360
  9. 811
  10. 840
  11. 1118
  12. 867
  13. 842
  14. 192
  15. 887
  16. 380
  17. 446
  18. 104
  19. 395
  20. 435
  21. 601
  22. 212
  23. 1131
  24. 831
  25. 307
  26. 506
  27. 184
  28. 778
  29. 514
  30. 671
  31. 711
  32. 393
  33. 521
  34. 426
  35. 432
  36. 463
  37. 654
  38. 1113
  39. 804
  40. 313

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