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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 842 · 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. 1.593 − 481 =
  2. 2.682 + 352 =
  3. 3.612 − 167 =
  4. 4.659 + 186 =
  5. 5.902 − 582 =
  6. 6.732 − 347 =
  7. 7.302 + 536 =
  8. 8.672 − 325 =
  9. 9.460 + 385 =
  10. 10.197 + 363 =
  11. 11.281 + 157 =
  12. 12.500 + 641 =
  13. 13.868 − 361 =
  14. 14.942 − 311 =
  15. 15.551 + 442 =
  16. 16.581 + 318 =
  17. 17.216 + 299 =
  18. 18.204 + 168 =
  19. 19.185 + 399 =
  20. 20.733 − 132 =
  21. 21.846 − 156 =
  22. 22.452 − 163 =
  23. 23.495 − 251 =
  24. 24.377 + 291 =
  25. 25.494 + 454 =
  26. 26.326 + 455 =
  27. 27.766 − 202 =
  28. 28.417 − 137 =
  29. 29.667 + 301 =
  30. 30.966 − 787 =
  31. 31.693 − 431 =
  32. 32.504 + 213 =
  33. 33.943 − 502 =
  34. 34.570 − 326 =
  35. 35.778 + 252 =
  36. 36.592 + 234 =
  37. 37.538 − 374 =
  38. 38.594 − 385 =
  39. 39.252 + 164 =
  40. 40.233 + 202 =

Answer key

  1. 112
  2. 1034
  3. 445
  4. 845
  5. 320
  6. 385
  7. 838
  8. 347
  9. 845
  10. 560
  11. 438
  12. 1141
  13. 507
  14. 631
  15. 993
  16. 899
  17. 515
  18. 372
  19. 584
  20. 601
  21. 690
  22. 289
  23. 244
  24. 668
  25. 948
  26. 781
  27. 564
  28. 280
  29. 968
  30. 179
  31. 262
  32. 717
  33. 441
  34. 244
  35. 1030
  36. 826
  37. 164
  38. 209
  39. 416
  40. 435

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