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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 151 · 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. 1.350 + 209 =
  2. 2.981 − 724 =
  3. 3.966 − 168 =
  4. 4.831 − 162 =
  5. 5.150 + 188 =
  6. 6.757 + 295 =
  7. 7.422 + 251 =
  8. 8.439 + 293 =
  9. 9.464 − 235 =
  10. 10.420 − 131 =
  11. 11.611 − 509 =
  12. 12.663 + 678 =
  13. 13.298 + 377 =
  14. 14.866 − 697 =
  15. 15.140 + 286 =
  16. 16.711 − 392 =
  17. 17.726 − 198 =
  18. 18.857 − 366 =
  19. 19.264 + 392 =
  20. 20.877 − 126 =
  21. 21.149 + 127 =
  22. 22.147 + 306 =
  23. 23.981 − 397 =
  24. 24.535 − 291 =
  25. 25.751 − 171 =
  26. 26.554 + 586 =
  27. 27.266 + 512 =
  28. 28.620 − 281 =
  29. 29.563 − 202 =
  30. 30.803 − 349 =
  31. 31.640 + 204 =
  32. 32.431 − 249 =
  33. 33.467 + 211 =
  34. 34.555 − 435 =
  35. 35.810 − 371 =
  36. 36.170 + 207 =
  37. 37.845 − 215 =
  38. 38.753 + 688 =
  39. 39.422 − 197 =
  40. 40.772 + 414 =

Answer key

  1. 559
  2. 257
  3. 798
  4. 669
  5. 338
  6. 1052
  7. 673
  8. 732
  9. 229
  10. 289
  11. 102
  12. 1341
  13. 675
  14. 169
  15. 426
  16. 319
  17. 528
  18. 491
  19. 656
  20. 751
  21. 276
  22. 453
  23. 584
  24. 244
  25. 580
  26. 1140
  27. 778
  28. 339
  29. 361
  30. 454
  31. 844
  32. 182
  33. 678
  34. 120
  35. 439
  36. 377
  37. 630
  38. 1441
  39. 225
  40. 1186

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