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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 247 · 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. 1.546 − 213 =
  2. 2.334 + 503 =
  3. 3.688 + 219 =
  4. 4.250 + 291 =
  5. 5.217 + 562 =
  6. 6.151 + 394 =
  7. 7.433 − 151 =
  8. 8.644 + 537 =
  9. 9.622 + 655 =
  10. 10.340 + 421 =
  11. 11.356 + 385 =
  12. 12.732 − 437 =
  13. 13.759 − 135 =
  14. 14.419 − 154 =
  15. 15.799 − 212 =
  16. 16.650 − 394 =
  17. 17.239 + 176 =
  18. 18.699 − 391 =
  19. 19.532 + 175 =
  20. 20.413 + 661 =
  21. 21.578 − 329 =
  22. 22.308 + 207 =
  23. 23.645 − 157 =
  24. 24.432 + 406 =
  25. 25.977 − 846 =
  26. 26.227 + 291 =
  27. 27.923 − 201 =
  28. 28.306 + 361 =
  29. 29.835 − 256 =
  30. 30.335 + 131 =
  31. 31.785 + 532 =
  32. 32.870 − 471 =
  33. 33.515 − 355 =
  34. 34.132 + 441 =
  35. 35.343 + 591 =
  36. 36.756 + 593 =
  37. 37.480 + 375 =
  38. 38.706 − 284 =
  39. 39.619 + 655 =
  40. 40.413 + 143 =

Answer key

  1. 333
  2. 837
  3. 907
  4. 541
  5. 779
  6. 545
  7. 282
  8. 1181
  9. 1277
  10. 761
  11. 741
  12. 295
  13. 624
  14. 265
  15. 587
  16. 256
  17. 415
  18. 308
  19. 707
  20. 1074
  21. 249
  22. 515
  23. 488
  24. 838
  25. 131
  26. 518
  27. 722
  28. 667
  29. 579
  30. 466
  31. 1317
  32. 399
  33. 160
  34. 573
  35. 934
  36. 1349
  37. 855
  38. 422
  39. 1274
  40. 556

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