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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 294 · 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. 1.427 − 239 =
  2. 2.843 − 535 =
  3. 3.517 − 377 =
  4. 4.265 + 332 =
  5. 5.515 + 494 =
  6. 6.528 − 321 =
  7. 7.542 − 298 =
  8. 8.521 − 382 =
  9. 9.717 − 316 =
  10. 10.441 + 414 =
  11. 11.483 + 208 =
  12. 12.458 + 407 =
  13. 13.670 − 484 =
  14. 14.313 + 547 =
  15. 15.741 − 558 =
  16. 16.563 − 383 =
  17. 17.419 + 145 =
  18. 18.495 − 225 =
  19. 19.220 + 521 =
  20. 20.393 + 579 =
  21. 21.983 − 281 =
  22. 22.575 + 428 =
  23. 23.503 − 321 =
  24. 24.497 − 139 =
  25. 25.772 + 196 =
  26. 26.770 − 529 =
  27. 27.631 + 377 =
  28. 28.221 + 491 =
  29. 29.275 + 646 =
  30. 30.907 − 777 =
  31. 31.169 + 321 =
  32. 32.558 − 208 =
  33. 33.145 + 138 =
  34. 34.727 − 603 =
  35. 35.832 − 687 =
  36. 36.947 − 696 =
  37. 37.746 + 204 =
  38. 38.558 − 396 =
  39. 39.568 − 292 =
  40. 40.312 + 118 =

Answer key

  1. 188
  2. 308
  3. 140
  4. 597
  5. 1009
  6. 207
  7. 244
  8. 139
  9. 401
  10. 855
  11. 691
  12. 865
  13. 186
  14. 860
  15. 183
  16. 180
  17. 564
  18. 270
  19. 741
  20. 972
  21. 702
  22. 1003
  23. 182
  24. 358
  25. 968
  26. 241
  27. 1008
  28. 712
  29. 921
  30. 130
  31. 490
  32. 350
  33. 283
  34. 124
  35. 145
  36. 251
  37. 950
  38. 162
  39. 276
  40. 430

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