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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 42 · 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. 1.282 + 314 =
  2. 2.747 − 437 =
  3. 3.315 + 465 =
  4. 4.658 + 359 =
  5. 5.476 − 295 =
  6. 6.474 − 302 =
  7. 7.477 − 141 =
  8. 8.624 − 507 =
  9. 9.483 − 241 =
  10. 10.622 + 436 =
  11. 11.972 − 841 =
  12. 12.730 + 285 =
  13. 13.744 − 595 =
  14. 14.450 − 269 =
  15. 15.128 + 218 =
  16. 16.206 + 405 =
  17. 17.608 + 647 =
  18. 18.703 − 185 =
  19. 19.812 − 573 =
  20. 20.564 − 454 =
  21. 21.562 + 151 =
  22. 22.287 + 638 =
  23. 23.233 + 636 =
  24. 24.215 + 271 =
  25. 25.878 − 238 =
  26. 26.549 − 139 =
  27. 27.980 − 579 =
  28. 28.593 + 604 =
  29. 29.621 + 477 =
  30. 30.437 − 211 =
  31. 31.566 + 269 =
  32. 32.621 − 255 =
  33. 33.445 + 243 =
  34. 34.308 + 683 =
  35. 35.692 + 349 =
  36. 36.328 + 571 =
  37. 37.548 + 331 =
  38. 38.430 + 299 =
  39. 39.535 − 341 =
  40. 40.819 − 469 =

Answer key

  1. 596
  2. 310
  3. 780
  4. 1017
  5. 181
  6. 172
  7. 336
  8. 117
  9. 242
  10. 1058
  11. 131
  12. 1015
  13. 149
  14. 181
  15. 346
  16. 611
  17. 1255
  18. 518
  19. 239
  20. 110
  21. 713
  22. 925
  23. 869
  24. 486
  25. 640
  26. 410
  27. 401
  28. 1197
  29. 1098
  30. 226
  31. 835
  32. 366
  33. 688
  34. 991
  35. 1041
  36. 899
  37. 879
  38. 729
  39. 194
  40. 350

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