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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 337 · 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. 1.463 + 571 =
  2. 2.173 + 177 =
  3. 3.761 − 501 =
  4. 4.348 + 143 =
  5. 5.915 − 112 =
  6. 6.177 + 658 =
  7. 7.139 + 598 =
  8. 8.550 + 275 =
  9. 9.713 + 264 =
  10. 10.203 + 294 =
  11. 11.378 + 176 =
  12. 12.952 − 541 =
  13. 13.867 − 421 =
  14. 14.979 − 323 =
  15. 15.150 + 229 =
  16. 16.417 − 218 =
  17. 17.610 + 265 =
  18. 18.614 + 235 =
  19. 19.171 + 242 =
  20. 20.576 − 271 =
  21. 21.339 + 645 =
  22. 22.270 + 686 =
  23. 23.544 − 218 =
  24. 24.452 − 195 =
  25. 25.507 + 555 =
  26. 26.987 − 802 =
  27. 27.858 − 619 =
  28. 28.983 − 794 =
  29. 29.735 + 211 =
  30. 30.961 − 358 =
  31. 31.213 + 341 =
  32. 32.528 − 391 =
  33. 33.672 − 182 =
  34. 34.480 − 368 =
  35. 35.846 − 488 =
  36. 36.720 − 376 =
  37. 37.292 + 574 =
  38. 38.860 − 134 =
  39. 39.686 + 372 =
  40. 40.615 − 497 =

Answer key

  1. 1034
  2. 350
  3. 260
  4. 491
  5. 803
  6. 835
  7. 737
  8. 825
  9. 977
  10. 497
  11. 554
  12. 411
  13. 446
  14. 656
  15. 379
  16. 199
  17. 875
  18. 849
  19. 413
  20. 305
  21. 984
  22. 956
  23. 326
  24. 257
  25. 1062
  26. 185
  27. 239
  28. 189
  29. 946
  30. 603
  31. 554
  32. 137
  33. 490
  34. 112
  35. 358
  36. 344
  37. 866
  38. 726
  39. 1058
  40. 118

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