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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 965 · 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. 1.901 − 671 =
  2. 2.433 − 239 =
  3. 3.764 − 188 =
  4. 4.383 + 455 =
  5. 5.757 + 445 =
  6. 6.766 + 386 =
  7. 7.181 + 243 =
  8. 8.785 − 115 =
  9. 9.256 + 143 =
  10. 10.288 + 361 =
  11. 11.324 + 544 =
  12. 12.692 + 445 =
  13. 13.557 − 241 =
  14. 14.769 + 559 =
  15. 15.305 + 133 =
  16. 16.465 − 214 =
  17. 17.261 + 555 =
  18. 18.601 − 226 =
  19. 19.218 + 352 =
  20. 20.907 − 261 =
  21. 21.402 + 617 =
  22. 22.627 − 113 =
  23. 23.352 + 644 =
  24. 24.817 − 337 =
  25. 25.754 − 523 =
  26. 26.582 − 156 =
  27. 27.744 − 376 =
  28. 28.640 − 411 =
  29. 29.724 − 151 =
  30. 30.491 − 273 =
  31. 31.461 + 622 =
  32. 32.795 − 393 =
  33. 33.956 − 252 =
  34. 34.739 − 545 =
  35. 35.641 − 331 =
  36. 36.781 − 181 =
  37. 37.478 − 324 =
  38. 38.526 + 372 =
  39. 39.241 + 268 =
  40. 40.729 + 245 =

Answer key

  1. 230
  2. 194
  3. 576
  4. 838
  5. 1202
  6. 1152
  7. 424
  8. 670
  9. 399
  10. 649
  11. 868
  12. 1137
  13. 316
  14. 1328
  15. 438
  16. 251
  17. 816
  18. 375
  19. 570
  20. 646
  21. 1019
  22. 514
  23. 996
  24. 480
  25. 231
  26. 426
  27. 368
  28. 229
  29. 573
  30. 218
  31. 1083
  32. 402
  33. 704
  34. 194
  35. 310
  36. 600
  37. 154
  38. 898
  39. 509
  40. 974

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