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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 863 · 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. 1.845 − 154 =
  2. 2.547 + 487 =
  3. 3.602 + 123 =
  4. 4.967 − 326 =
  5. 5.617 + 457 =
  6. 6.545 + 359 =
  7. 7.683 + 392 =
  8. 8.784 + 354 =
  9. 9.914 − 678 =
  10. 10.310 + 543 =
  11. 11.772 + 161 =
  12. 12.768 + 208 =
  13. 13.389 + 182 =
  14. 14.533 + 471 =
  15. 15.491 − 391 =
  16. 16.638 + 255 =
  17. 17.248 + 262 =
  18. 18.571 + 601 =
  19. 19.140 + 387 =
  20. 20.605 + 612 =
  21. 21.239 + 134 =
  22. 22.353 + 526 =
  23. 23.693 + 406 =
  24. 24.452 + 351 =
  25. 25.375 + 611 =
  26. 26.576 + 121 =
  27. 27.179 + 216 =
  28. 28.511 − 143 =
  29. 29.646 + 433 =
  30. 30.547 − 169 =
  31. 31.137 + 626 =
  32. 32.755 − 603 =
  33. 33.461 − 261 =
  34. 34.744 − 362 =
  35. 35.319 + 508 =
  36. 36.357 + 151 =
  37. 37.638 − 245 =
  38. 38.427 + 431 =
  39. 39.453 − 195 =
  40. 40.735 + 517 =

Answer key

  1. 691
  2. 1034
  3. 725
  4. 641
  5. 1074
  6. 904
  7. 1075
  8. 1138
  9. 236
  10. 853
  11. 933
  12. 976
  13. 571
  14. 1004
  15. 100
  16. 893
  17. 510
  18. 1172
  19. 527
  20. 1217
  21. 373
  22. 879
  23. 1099
  24. 803
  25. 986
  26. 697
  27. 395
  28. 368
  29. 1079
  30. 378
  31. 763
  32. 152
  33. 200
  34. 382
  35. 827
  36. 508
  37. 393
  38. 858
  39. 258
  40. 1252

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