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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 461 · 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. 1.830 − 148 =
  2. 2.414 − 286 =
  3. 3.955 − 128 =
  4. 4.683 + 412 =
  5. 5.758 + 403 =
  6. 6.534 − 388 =
  7. 7.708 − 171 =
  8. 8.516 + 511 =
  9. 9.604 + 217 =
  10. 10.891 − 696 =
  11. 11.936 − 306 =
  12. 12.953 − 206 =
  13. 13.740 + 521 =
  14. 14.692 − 409 =
  15. 15.781 + 187 =
  16. 16.414 + 689 =
  17. 17.194 + 119 =
  18. 18.565 + 393 =
  19. 19.770 − 596 =
  20. 20.256 + 284 =
  21. 21.724 − 366 =
  22. 22.200 + 617 =
  23. 23.748 − 527 =
  24. 24.981 − 512 =
  25. 25.591 + 513 =
  26. 26.604 − 161 =
  27. 27.801 − 258 =
  28. 28.971 − 595 =
  29. 29.815 − 159 =
  30. 30.264 + 175 =
  31. 31.499 + 395 =
  32. 32.388 + 454 =
  33. 33.975 − 255 =
  34. 34.947 − 271 =
  35. 35.251 + 595 =
  36. 36.295 + 352 =
  37. 37.169 + 204 =
  38. 38.698 − 592 =
  39. 39.439 + 211 =
  40. 40.363 + 542 =

Answer key

  1. 682
  2. 128
  3. 827
  4. 1095
  5. 1161
  6. 146
  7. 537
  8. 1027
  9. 821
  10. 195
  11. 630
  12. 747
  13. 1261
  14. 283
  15. 968
  16. 1103
  17. 313
  18. 958
  19. 174
  20. 540
  21. 358
  22. 817
  23. 221
  24. 469
  25. 1104
  26. 443
  27. 543
  28. 376
  29. 656
  30. 439
  31. 894
  32. 842
  33. 720
  34. 676
  35. 846
  36. 647
  37. 373
  38. 106
  39. 650
  40. 905

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