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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 244 · 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. 1.436 + 382 =
  2. 2.496 − 141 =
  3. 3.716 + 141 =
  4. 4.302 + 332 =
  5. 5.921 − 178 =
  6. 6.498 + 431 =
  7. 7.443 + 286 =
  8. 8.544 − 327 =
  9. 9.702 + 647 =
  10. 10.157 + 465 =
  11. 11.432 + 472 =
  12. 12.626 + 252 =
  13. 13.433 + 537 =
  14. 14.960 − 282 =
  15. 15.583 − 115 =
  16. 16.742 + 122 =
  17. 17.766 + 427 =
  18. 18.576 − 218 =
  19. 19.650 − 472 =
  20. 20.368 + 251 =
  21. 21.266 + 614 =
  22. 22.356 + 441 =
  23. 23.261 + 233 =
  24. 24.810 − 191 =
  25. 25.600 + 406 =
  26. 26.124 + 652 =
  27. 27.969 − 214 =
  28. 28.505 − 353 =
  29. 29.929 − 212 =
  30. 30.335 + 608 =
  31. 31.969 − 477 =
  32. 32.557 − 172 =
  33. 33.688 + 265 =
  34. 34.313 + 136 =
  35. 35.665 − 344 =
  36. 36.146 + 488 =
  37. 37.202 + 514 =
  38. 38.538 − 291 =
  39. 39.764 + 308 =
  40. 40.659 − 453 =

Answer key

  1. 818
  2. 355
  3. 857
  4. 634
  5. 743
  6. 929
  7. 729
  8. 217
  9. 1349
  10. 622
  11. 904
  12. 878
  13. 970
  14. 678
  15. 468
  16. 864
  17. 1193
  18. 358
  19. 178
  20. 619
  21. 880
  22. 797
  23. 494
  24. 619
  25. 1006
  26. 776
  27. 755
  28. 152
  29. 717
  30. 943
  31. 492
  32. 385
  33. 953
  34. 449
  35. 321
  36. 634
  37. 716
  38. 247
  39. 1072
  40. 206

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