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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 435 · 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. 1.856 − 418 =
  2. 2.817 − 615 =
  3. 3.733 + 576 =
  4. 4.762 + 121 =
  5. 5.744 − 264 =
  6. 6.194 + 224 =
  7. 7.740 − 421 =
  8. 8.809 − 602 =
  9. 9.425 + 252 =
  10. 10.228 + 549 =
  11. 11.374 + 217 =
  12. 12.545 + 174 =
  13. 13.309 + 524 =
  14. 14.699 + 342 =
  15. 15.160 + 479 =
  16. 16.168 + 515 =
  17. 17.739 − 593 =
  18. 18.921 − 189 =
  19. 19.463 + 474 =
  20. 20.766 − 131 =
  21. 21.646 − 191 =
  22. 22.247 + 529 =
  23. 23.207 + 171 =
  24. 24.482 − 199 =
  25. 25.977 − 251 =
  26. 26.428 − 314 =
  27. 27.462 + 322 =
  28. 28.690 − 581 =
  29. 29.203 + 155 =
  30. 30.218 + 415 =
  31. 31.351 + 541 =
  32. 32.228 + 481 =
  33. 33.820 − 366 =
  34. 34.364 + 231 =
  35. 35.420 − 317 =
  36. 36.154 + 265 =
  37. 37.888 − 383 =
  38. 38.310 + 609 =
  39. 39.426 + 585 =
  40. 40.458 + 494 =

Answer key

  1. 438
  2. 202
  3. 1309
  4. 883
  5. 480
  6. 418
  7. 319
  8. 207
  9. 677
  10. 777
  11. 591
  12. 719
  13. 833
  14. 1041
  15. 639
  16. 683
  17. 146
  18. 732
  19. 937
  20. 635
  21. 455
  22. 776
  23. 378
  24. 283
  25. 726
  26. 114
  27. 784
  28. 109
  29. 358
  30. 633
  31. 892
  32. 709
  33. 454
  34. 595
  35. 103
  36. 419
  37. 505
  38. 919
  39. 1011
  40. 952

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