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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 486 · 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. 1.728 − 592 =
  2. 2.555 − 433 =
  3. 3.969 − 181 =
  4. 4.655 + 669 =
  5. 5.695 − 161 =
  6. 6.574 − 131 =
  7. 7.482 − 153 =
  8. 8.685 + 571 =
  9. 9.968 − 336 =
  10. 10.935 − 497 =
  11. 11.386 + 174 =
  12. 12.346 + 285 =
  13. 13.874 − 415 =
  14. 14.494 − 299 =
  15. 15.350 + 275 =
  16. 16.706 − 391 =
  17. 17.213 + 371 =
  18. 18.793 − 193 =
  19. 19.534 − 171 =
  20. 20.178 + 661 =
  21. 21.704 − 172 =
  22. 22.631 − 258 =
  23. 23.315 + 591 =
  24. 24.202 + 148 =
  25. 25.838 − 264 =
  26. 26.440 − 121 =
  27. 27.407 + 566 =
  28. 28.718 + 625 =
  29. 29.497 + 653 =
  30. 30.555 − 448 =
  31. 31.717 + 281 =
  32. 32.923 − 558 =
  33. 33.753 + 684 =
  34. 34.435 − 286 =
  35. 35.454 + 321 =
  36. 36.127 + 263 =
  37. 37.703 + 247 =
  38. 38.767 − 215 =
  39. 39.554 + 641 =
  40. 40.503 − 325 =

Answer key

  1. 136
  2. 122
  3. 788
  4. 1324
  5. 534
  6. 443
  7. 329
  8. 1256
  9. 632
  10. 438
  11. 560
  12. 631
  13. 459
  14. 195
  15. 625
  16. 315
  17. 584
  18. 600
  19. 363
  20. 839
  21. 532
  22. 373
  23. 906
  24. 350
  25. 574
  26. 319
  27. 973
  28. 1343
  29. 1150
  30. 107
  31. 998
  32. 365
  33. 1437
  34. 149
  35. 775
  36. 390
  37. 950
  38. 552
  39. 1195
  40. 178

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