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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 735 · 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. 1.754 − 179 =
  2. 2.831 − 246 =
  3. 3.620 − 288 =
  4. 4.512 − 151 =
  5. 5.656 + 145 =
  6. 6.412 + 161 =
  7. 7.622 − 152 =
  8. 8.655 − 155 =
  9. 9.907 − 126 =
  10. 10.768 + 519 =
  11. 11.602 − 265 =
  12. 12.178 + 544 =
  13. 13.503 + 248 =
  14. 14.926 − 242 =
  15. 15.366 + 616 =
  16. 16.482 − 193 =
  17. 17.791 − 605 =
  18. 18.665 − 532 =
  19. 19.689 + 211 =
  20. 20.522 − 194 =
  21. 21.453 + 368 =
  22. 22.598 − 282 =
  23. 23.199 + 606 =
  24. 24.586 − 301 =
  25. 25.779 + 522 =
  26. 26.521 − 331 =
  27. 27.762 + 274 =
  28. 28.505 + 183 =
  29. 29.351 + 628 =
  30. 30.564 − 158 =
  31. 31.220 + 208 =
  32. 32.656 + 247 =
  33. 33.857 − 113 =
  34. 34.160 + 421 =
  35. 35.674 + 424 =
  36. 36.394 + 493 =
  37. 37.309 + 461 =
  38. 38.509 + 619 =
  39. 39.437 + 628 =
  40. 40.552 + 502 =

Answer key

  1. 575
  2. 585
  3. 332
  4. 361
  5. 801
  6. 573
  7. 470
  8. 500
  9. 781
  10. 1287
  11. 337
  12. 722
  13. 751
  14. 684
  15. 982
  16. 289
  17. 186
  18. 133
  19. 900
  20. 328
  21. 821
  22. 316
  23. 805
  24. 285
  25. 1301
  26. 190
  27. 1036
  28. 688
  29. 979
  30. 406
  31. 428
  32. 903
  33. 744
  34. 581
  35. 1098
  36. 887
  37. 770
  38. 1128
  39. 1065
  40. 1054

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