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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 482 · 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. 1.249 + 338 =
  2. 2.499 + 237 =
  3. 3.289 + 426 =
  4. 4.603 − 161 =
  5. 5.778 − 652 =
  6. 6.709 + 353 =
  7. 7.405 + 594 =
  8. 8.283 + 623 =
  9. 9.826 − 515 =
  10. 10.534 − 149 =
  11. 11.581 + 221 =
  12. 12.673 − 455 =
  13. 13.568 + 113 =
  14. 14.586 − 301 =
  15. 15.479 + 529 =
  16. 16.468 − 333 =
  17. 17.239 + 363 =
  18. 18.463 + 226 =
  19. 19.567 + 615 =
  20. 20.180 + 247 =
  21. 21.814 − 528 =
  22. 22.824 − 284 =
  23. 23.638 + 461 =
  24. 24.554 + 381 =
  25. 25.716 + 671 =
  26. 26.458 − 183 =
  27. 27.777 − 638 =
  28. 28.327 + 155 =
  29. 29.252 + 226 =
  30. 30.169 + 627 =
  31. 31.744 − 129 =
  32. 32.592 + 237 =
  33. 33.883 − 363 =
  34. 34.567 + 481 =
  35. 35.744 − 584 =
  36. 36.320 + 367 =
  37. 37.589 + 497 =
  38. 38.695 + 162 =
  39. 39.446 − 279 =
  40. 40.461 − 301 =

Answer key

  1. 587
  2. 736
  3. 715
  4. 442
  5. 126
  6. 1062
  7. 999
  8. 906
  9. 311
  10. 385
  11. 802
  12. 218
  13. 681
  14. 285
  15. 1008
  16. 135
  17. 602
  18. 689
  19. 1182
  20. 427
  21. 286
  22. 540
  23. 1099
  24. 935
  25. 1387
  26. 275
  27. 139
  28. 482
  29. 478
  30. 796
  31. 615
  32. 829
  33. 520
  34. 1048
  35. 160
  36. 687
  37. 1086
  38. 857
  39. 167
  40. 160

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