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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 319 · 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. 1.699 − 597 =
  2. 2.155 + 201 =
  3. 3.953 − 156 =
  4. 4.650 + 396 =
  5. 5.572 + 281 =
  6. 6.910 − 674 =
  7. 7.275 + 157 =
  8. 8.144 + 169 =
  9. 9.639 + 468 =
  10. 10.287 + 201 =
  11. 11.879 − 119 =
  12. 12.888 − 573 =
  13. 13.749 − 185 =
  14. 14.655 − 319 =
  15. 15.480 + 322 =
  16. 16.963 − 222 =
  17. 17.555 − 295 =
  18. 18.621 + 151 =
  19. 19.389 + 654 =
  20. 20.491 + 278 =
  21. 21.451 − 131 =
  22. 22.454 + 612 =
  23. 23.410 + 226 =
  24. 24.389 + 177 =
  25. 25.500 − 333 =
  26. 26.838 − 164 =
  27. 27.628 − 397 =
  28. 28.638 − 189 =
  29. 29.246 + 535 =
  30. 30.473 + 558 =
  31. 31.881 − 526 =
  32. 32.217 + 636 =
  33. 33.743 + 602 =
  34. 34.945 − 828 =
  35. 35.966 − 445 =
  36. 36.551 + 154 =
  37. 37.753 − 329 =
  38. 38.435 − 125 =
  39. 39.465 − 358 =
  40. 40.671 + 217 =

Answer key

  1. 102
  2. 356
  3. 797
  4. 1046
  5. 853
  6. 236
  7. 432
  8. 313
  9. 1107
  10. 488
  11. 760
  12. 315
  13. 564
  14. 336
  15. 802
  16. 741
  17. 260
  18. 772
  19. 1043
  20. 769
  21. 320
  22. 1066
  23. 636
  24. 566
  25. 167
  26. 674
  27. 231
  28. 449
  29. 781
  30. 1031
  31. 355
  32. 853
  33. 1345
  34. 117
  35. 521
  36. 705
  37. 424
  38. 310
  39. 107
  40. 888

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