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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 969 · 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. 1.224 + 588 =
  2. 2.799 − 395 =
  3. 3.647 + 213 =
  4. 4.631 − 256 =
  5. 5.801 − 238 =
  6. 6.910 − 379 =
  7. 7.204 + 666 =
  8. 8.585 − 239 =
  9. 9.520 + 667 =
  10. 10.527 − 377 =
  11. 11.476 + 233 =
  12. 12.265 + 221 =
  13. 13.670 + 618 =
  14. 14.236 + 639 =
  15. 15.425 + 277 =
  16. 16.538 + 622 =
  17. 17.983 − 185 =
  18. 18.816 − 251 =
  19. 19.490 − 136 =
  20. 20.929 − 469 =
  21. 21.713 + 561 =
  22. 22.152 + 228 =
  23. 23.776 + 182 =
  24. 24.599 − 425 =
  25. 25.457 + 552 =
  26. 26.789 − 315 =
  27. 27.781 − 282 =
  28. 28.316 + 346 =
  29. 29.176 + 543 =
  30. 30.395 + 272 =
  31. 31.144 + 559 =
  32. 32.880 − 173 =
  33. 33.524 − 192 =
  34. 34.690 + 546 =
  35. 35.727 + 232 =
  36. 36.185 + 246 =
  37. 37.425 + 447 =
  38. 38.315 + 574 =
  39. 39.596 + 453 =
  40. 40.581 + 227 =

Answer key

  1. 812
  2. 404
  3. 860
  4. 375
  5. 563
  6. 531
  7. 870
  8. 346
  9. 1187
  10. 150
  11. 709
  12. 486
  13. 1288
  14. 875
  15. 702
  16. 1160
  17. 798
  18. 565
  19. 354
  20. 460
  21. 1274
  22. 380
  23. 958
  24. 174
  25. 1009
  26. 474
  27. 499
  28. 662
  29. 719
  30. 667
  31. 703
  32. 707
  33. 332
  34. 1236
  35. 959
  36. 431
  37. 872
  38. 889
  39. 1049
  40. 808

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