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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 424 · 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. 1.654 + 396 =
  2. 2.627 + 644 =
  3. 3.755 + 676 =
  4. 4.868 − 231 =
  5. 5.461 + 229 =
  6. 6.195 + 473 =
  7. 7.910 − 132 =
  8. 8.730 − 567 =
  9. 9.135 + 466 =
  10. 10.582 − 121 =
  11. 11.193 + 151 =
  12. 12.514 − 281 =
  13. 13.610 − 492 =
  14. 14.453 + 663 =
  15. 15.177 + 126 =
  16. 16.279 + 216 =
  17. 17.382 + 565 =
  18. 18.722 − 307 =
  19. 19.154 + 677 =
  20. 20.636 − 491 =
  21. 21.735 + 182 =
  22. 22.442 + 448 =
  23. 23.356 + 203 =
  24. 24.462 − 191 =
  25. 25.287 + 173 =
  26. 26.952 − 654 =
  27. 27.620 − 344 =
  28. 28.770 + 668 =
  29. 29.272 + 206 =
  30. 30.960 − 277 =
  31. 31.629 − 386 =
  32. 32.459 − 314 =
  33. 33.534 + 212 =
  34. 34.706 + 485 =
  35. 35.594 + 531 =
  36. 36.490 + 575 =
  37. 37.698 − 477 =
  38. 38.237 + 309 =
  39. 39.523 − 124 =
  40. 40.846 − 371 =

Answer key

  1. 1050
  2. 1271
  3. 1431
  4. 637
  5. 690
  6. 668
  7. 778
  8. 163
  9. 601
  10. 461
  11. 344
  12. 233
  13. 118
  14. 1116
  15. 303
  16. 495
  17. 947
  18. 415
  19. 831
  20. 145
  21. 917
  22. 890
  23. 559
  24. 271
  25. 460
  26. 298
  27. 276
  28. 1438
  29. 478
  30. 683
  31. 243
  32. 145
  33. 746
  34. 1191
  35. 1125
  36. 1065
  37. 221
  38. 546
  39. 399
  40. 475

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