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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 620 · 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. 1.309 + 281 =
  2. 2.660 + 341 =
  3. 3.509 + 459 =
  4. 4.508 − 125 =
  5. 5.219 + 159 =
  6. 6.457 − 351 =
  7. 7.422 + 601 =
  8. 8.963 − 116 =
  9. 9.130 + 597 =
  10. 10.811 − 527 =
  11. 11.645 + 416 =
  12. 12.751 − 561 =
  13. 13.291 + 487 =
  14. 14.290 + 593 =
  15. 15.594 + 251 =
  16. 16.959 − 197 =
  17. 17.963 − 202 =
  18. 18.341 + 305 =
  19. 19.134 + 588 =
  20. 20.754 + 141 =
  21. 21.554 − 417 =
  22. 22.275 + 208 =
  23. 23.428 + 631 =
  24. 24.733 − 126 =
  25. 25.331 + 362 =
  26. 26.161 + 431 =
  27. 27.884 − 224 =
  28. 28.518 − 163 =
  29. 29.891 − 238 =
  30. 30.407 + 122 =
  31. 31.949 − 432 =
  32. 32.875 − 402 =
  33. 33.663 − 164 =
  34. 34.853 − 543 =
  35. 35.481 + 622 =
  36. 36.338 + 524 =
  37. 37.542 − 336 =
  38. 38.789 + 401 =
  39. 39.432 + 625 =
  40. 40.773 + 568 =

Answer key

  1. 590
  2. 1001
  3. 968
  4. 383
  5. 378
  6. 106
  7. 1023
  8. 847
  9. 727
  10. 284
  11. 1061
  12. 190
  13. 778
  14. 883
  15. 845
  16. 762
  17. 761
  18. 646
  19. 722
  20. 895
  21. 137
  22. 483
  23. 1059
  24. 607
  25. 693
  26. 592
  27. 660
  28. 355
  29. 653
  30. 529
  31. 517
  32. 473
  33. 499
  34. 310
  35. 1103
  36. 862
  37. 206
  38. 1190
  39. 1057
  40. 1341

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