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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 266 · 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. 1.196 + 553 =
  2. 2.133 + 152 =
  3. 3.132 + 195 =
  4. 4.647 + 161 =
  5. 5.547 − 168 =
  6. 6.663 + 219 =
  7. 7.397 + 546 =
  8. 8.794 − 237 =
  9. 9.582 + 148 =
  10. 10.888 − 126 =
  11. 11.723 + 561 =
  12. 12.875 − 187 =
  13. 13.394 + 184 =
  14. 14.293 + 173 =
  15. 15.417 − 169 =
  16. 16.492 − 199 =
  17. 17.349 + 436 =
  18. 18.589 + 311 =
  19. 19.232 + 158 =
  20. 20.465 + 243 =
  21. 21.463 − 326 =
  22. 22.976 − 219 =
  23. 23.572 + 647 =
  24. 24.593 − 304 =
  25. 25.490 − 202 =
  26. 26.524 − 193 =
  27. 27.756 − 319 =
  28. 28.866 − 509 =
  29. 29.582 + 483 =
  30. 30.356 + 285 =
  31. 31.713 − 584 =
  32. 32.832 − 323 =
  33. 33.564 + 641 =
  34. 34.756 + 523 =
  35. 35.298 + 335 =
  36. 36.735 − 421 =
  37. 37.716 − 513 =
  38. 38.716 − 257 =
  39. 39.911 − 208 =
  40. 40.470 − 155 =

Answer key

  1. 749
  2. 285
  3. 327
  4. 808
  5. 379
  6. 882
  7. 943
  8. 557
  9. 730
  10. 762
  11. 1284
  12. 688
  13. 578
  14. 466
  15. 248
  16. 293
  17. 785
  18. 900
  19. 390
  20. 708
  21. 137
  22. 757
  23. 1219
  24. 289
  25. 288
  26. 331
  27. 437
  28. 357
  29. 1065
  30. 641
  31. 129
  32. 509
  33. 1205
  34. 1279
  35. 633
  36. 314
  37. 203
  38. 459
  39. 703
  40. 315

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