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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 827 · 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. 1.302 + 376 =
  2. 2.477 − 324 =
  3. 3.476 − 121 =
  4. 4.525 + 268 =
  5. 5.531 − 206 =
  6. 6.575 − 249 =
  7. 7.696 + 426 =
  8. 8.300 + 587 =
  9. 9.841 − 277 =
  10. 10.709 − 448 =
  11. 11.869 − 272 =
  12. 12.554 + 261 =
  13. 13.784 − 339 =
  14. 14.126 + 616 =
  15. 15.676 − 469 =
  16. 16.158 + 211 =
  17. 17.779 + 474 =
  18. 18.304 + 331 =
  19. 19.972 − 361 =
  20. 20.603 − 261 =
  21. 21.669 − 542 =
  22. 22.216 + 486 =
  23. 23.576 + 569 =
  24. 24.593 − 176 =
  25. 25.285 + 172 =
  26. 26.765 − 551 =
  27. 27.549 − 223 =
  28. 28.805 − 587 =
  29. 29.220 + 561 =
  30. 30.257 + 252 =
  31. 31.493 − 141 =
  32. 32.634 − 138 =
  33. 33.237 + 579 =
  34. 34.351 + 599 =
  35. 35.519 + 403 =
  36. 36.530 + 686 =
  37. 37.793 − 388 =
  38. 38.314 + 247 =
  39. 39.412 + 153 =
  40. 40.554 − 403 =

Answer key

  1. 678
  2. 153
  3. 355
  4. 793
  5. 325
  6. 326
  7. 1122
  8. 887
  9. 564
  10. 261
  11. 597
  12. 815
  13. 445
  14. 742
  15. 207
  16. 369
  17. 1253
  18. 635
  19. 611
  20. 342
  21. 127
  22. 702
  23. 1145
  24. 417
  25. 457
  26. 214
  27. 326
  28. 218
  29. 781
  30. 509
  31. 352
  32. 496
  33. 816
  34. 950
  35. 922
  36. 1216
  37. 405
  38. 561
  39. 565
  40. 151

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