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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 481 · 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. 1.340 + 191 =
  2. 2.300 + 621 =
  3. 3.500 − 256 =
  4. 4.696 + 472 =
  5. 5.722 + 414 =
  6. 6.208 + 327 =
  7. 7.620 + 207 =
  8. 8.153 + 281 =
  9. 9.670 − 227 =
  10. 10.407 + 539 =
  11. 11.645 − 207 =
  12. 12.902 − 441 =
  13. 13.439 + 161 =
  14. 14.208 + 618 =
  15. 15.636 − 389 =
  16. 16.474 + 231 =
  17. 17.517 − 258 =
  18. 18.486 − 294 =
  19. 19.557 + 537 =
  20. 20.442 + 574 =
  21. 21.803 − 271 =
  22. 22.430 + 113 =
  23. 23.750 + 556 =
  24. 24.831 − 504 =
  25. 25.537 − 362 =
  26. 26.546 − 341 =
  27. 27.446 − 292 =
  28. 28.526 − 212 =
  29. 29.470 + 433 =
  30. 30.892 − 783 =
  31. 31.915 − 318 =
  32. 32.244 + 221 =
  33. 33.413 + 305 =
  34. 34.441 − 283 =
  35. 35.579 + 261 =
  36. 36.518 + 187 =
  37. 37.473 + 303 =
  38. 38.549 − 434 =
  39. 39.206 + 481 =
  40. 40.603 − 378 =

Answer key

  1. 531
  2. 921
  3. 244
  4. 1168
  5. 1136
  6. 535
  7. 827
  8. 434
  9. 443
  10. 946
  11. 438
  12. 461
  13. 600
  14. 826
  15. 247
  16. 705
  17. 259
  18. 192
  19. 1094
  20. 1016
  21. 532
  22. 543
  23. 1306
  24. 327
  25. 175
  26. 205
  27. 154
  28. 314
  29. 903
  30. 109
  31. 597
  32. 465
  33. 718
  34. 158
  35. 840
  36. 705
  37. 776
  38. 115
  39. 687
  40. 225

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