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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 228 · 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. 1.471 + 627 =
  2. 2.556 − 439 =
  3. 3.232 + 527 =
  4. 4.577 + 272 =
  5. 5.722 − 129 =
  6. 6.457 − 338 =
  7. 7.367 + 134 =
  8. 8.288 + 429 =
  9. 9.725 + 564 =
  10. 10.360 + 173 =
  11. 11.959 − 431 =
  12. 12.174 + 145 =
  13. 13.499 − 281 =
  14. 14.800 − 215 =
  15. 15.774 + 509 =
  16. 16.326 + 585 =
  17. 17.858 − 281 =
  18. 18.680 − 431 =
  19. 19.740 − 347 =
  20. 20.483 − 252 =
  21. 21.501 + 407 =
  22. 22.147 + 681 =
  23. 23.465 − 138 =
  24. 24.442 − 245 =
  25. 25.683 + 192 =
  26. 26.681 − 281 =
  27. 27.693 + 227 =
  28. 28.548 − 158 =
  29. 29.843 − 282 =
  30. 30.321 + 129 =
  31. 31.752 + 432 =
  32. 32.476 − 261 =
  33. 33.721 − 253 =
  34. 34.560 + 195 =
  35. 35.881 − 267 =
  36. 36.135 + 684 =
  37. 37.564 + 349 =
  38. 38.594 − 146 =
  39. 39.349 + 677 =
  40. 40.130 + 227 =

Answer key

  1. 1098
  2. 117
  3. 759
  4. 849
  5. 593
  6. 119
  7. 501
  8. 717
  9. 1289
  10. 533
  11. 528
  12. 319
  13. 218
  14. 585
  15. 1283
  16. 911
  17. 577
  18. 249
  19. 393
  20. 231
  21. 908
  22. 828
  23. 327
  24. 197
  25. 875
  26. 400
  27. 920
  28. 390
  29. 561
  30. 450
  31. 1184
  32. 215
  33. 468
  34. 755
  35. 614
  36. 819
  37. 913
  38. 448
  39. 1026
  40. 357

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