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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 837 · 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. 1.986 − 229 =
  2. 2.675 − 273 =
  3. 3.720 + 121 =
  4. 4.182 + 583 =
  5. 5.752 − 132 =
  6. 6.300 + 549 =
  7. 7.602 − 344 =
  8. 8.198 + 304 =
  9. 9.427 + 432 =
  10. 10.554 − 322 =
  11. 11.736 − 238 =
  12. 12.629 − 256 =
  13. 13.634 − 163 =
  14. 14.784 − 654 =
  15. 15.802 − 301 =
  16. 16.490 + 555 =
  17. 17.556 + 477 =
  18. 18.271 + 447 =
  19. 19.369 + 678 =
  20. 20.770 + 531 =
  21. 21.799 − 582 =
  22. 22.398 + 285 =
  23. 23.839 − 154 =
  24. 24.649 + 642 =
  25. 25.644 − 541 =
  26. 26.607 + 403 =
  27. 27.890 − 439 =
  28. 28.455 + 158 =
  29. 29.528 + 547 =
  30. 30.364 + 561 =
  31. 31.579 + 335 =
  32. 32.430 − 214 =
  33. 33.685 + 131 =
  34. 34.629 + 613 =
  35. 35.418 + 393 =
  36. 36.971 − 561 =
  37. 37.445 − 208 =
  38. 38.604 + 549 =
  39. 39.434 + 295 =
  40. 40.927 − 302 =

Answer key

  1. 757
  2. 402
  3. 841
  4. 765
  5. 620
  6. 849
  7. 258
  8. 502
  9. 859
  10. 232
  11. 498
  12. 373
  13. 471
  14. 130
  15. 501
  16. 1045
  17. 1033
  18. 718
  19. 1047
  20. 1301
  21. 217
  22. 683
  23. 685
  24. 1291
  25. 103
  26. 1010
  27. 451
  28. 613
  29. 1075
  30. 925
  31. 914
  32. 216
  33. 816
  34. 1242
  35. 811
  36. 410
  37. 237
  38. 1153
  39. 729
  40. 625

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