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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 48 · 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. 1.358 + 363 =
  2. 2.501 − 243 =
  3. 3.694 + 533 =
  4. 4.816 − 523 =
  5. 5.575 − 401 =
  6. 6.779 − 562 =
  7. 7.886 − 463 =
  8. 8.761 + 206 =
  9. 9.633 + 548 =
  10. 10.644 − 291 =
  11. 11.204 + 521 =
  12. 12.483 + 629 =
  13. 13.338 + 151 =
  14. 14.198 + 428 =
  15. 15.532 − 287 =
  16. 16.150 + 539 =
  17. 17.476 + 661 =
  18. 18.480 + 604 =
  19. 19.640 − 391 =
  20. 20.423 + 509 =
  21. 21.645 + 432 =
  22. 22.514 − 261 =
  23. 23.200 + 483 =
  24. 24.416 + 149 =
  25. 25.525 + 481 =
  26. 26.752 + 284 =
  27. 27.434 + 513 =
  28. 28.560 − 242 =
  29. 29.709 − 284 =
  30. 30.176 + 289 =
  31. 31.131 + 247 =
  32. 32.785 − 457 =
  33. 33.531 − 176 =
  34. 34.636 + 581 =
  35. 35.318 + 321 =
  36. 36.216 + 374 =
  37. 37.424 − 196 =
  38. 38.565 + 332 =
  39. 39.940 − 302 =
  40. 40.227 + 653 =

Answer key

  1. 721
  2. 258
  3. 1227
  4. 293
  5. 174
  6. 217
  7. 423
  8. 967
  9. 1181
  10. 353
  11. 725
  12. 1112
  13. 489
  14. 626
  15. 245
  16. 689
  17. 1137
  18. 1084
  19. 249
  20. 932
  21. 1077
  22. 253
  23. 683
  24. 565
  25. 1006
  26. 1036
  27. 947
  28. 318
  29. 425
  30. 465
  31. 378
  32. 328
  33. 355
  34. 1217
  35. 639
  36. 590
  37. 228
  38. 897
  39. 638
  40. 880

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