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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 360 · 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. 1.637 + 601 =
  2. 2.151 + 537 =
  3. 3.558 − 222 =
  4. 4.603 + 241 =
  5. 5.520 − 226 =
  6. 6.198 + 195 =
  7. 7.706 + 381 =
  8. 8.587 + 661 =
  9. 9.965 − 673 =
  10. 10.580 − 244 =
  11. 11.657 − 197 =
  12. 12.128 + 561 =
  13. 13.165 + 302 =
  14. 14.792 − 259 =
  15. 15.767 − 609 =
  16. 16.340 + 299 =
  17. 17.633 + 309 =
  18. 18.282 + 584 =
  19. 19.525 + 353 =
  20. 20.484 − 191 =
  21. 21.626 − 358 =
  22. 22.973 − 791 =
  23. 23.645 − 379 =
  24. 24.171 + 478 =
  25. 25.833 − 582 =
  26. 26.362 + 559 =
  27. 27.489 − 359 =
  28. 28.606 + 128 =
  29. 29.884 − 411 =
  30. 30.452 + 329 =
  31. 31.354 + 372 =
  32. 32.748 − 223 =
  33. 33.261 + 267 =
  34. 34.348 + 222 =
  35. 35.414 − 116 =
  36. 36.448 + 408 =
  37. 37.587 + 574 =
  38. 38.257 + 296 =
  39. 39.514 − 184 =
  40. 40.860 − 232 =

Answer key

  1. 1238
  2. 688
  3. 336
  4. 844
  5. 294
  6. 393
  7. 1087
  8. 1248
  9. 292
  10. 336
  11. 460
  12. 689
  13. 467
  14. 533
  15. 158
  16. 639
  17. 942
  18. 866
  19. 878
  20. 293
  21. 268
  22. 182
  23. 266
  24. 649
  25. 251
  26. 921
  27. 130
  28. 734
  29. 473
  30. 781
  31. 726
  32. 525
  33. 528
  34. 570
  35. 298
  36. 856
  37. 1161
  38. 553
  39. 330
  40. 628

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