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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 551 · 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. 1.150 + 481 =
  2. 2.412 + 134 =
  3. 3.420 − 131 =
  4. 4.446 − 338 =
  5. 5.447 + 234 =
  6. 6.838 − 687 =
  7. 7.669 + 124 =
  8. 8.263 + 514 =
  9. 9.944 − 811 =
  10. 10.533 + 307 =
  11. 11.243 + 178 =
  12. 12.613 + 447 =
  13. 13.716 − 231 =
  14. 14.899 − 354 =
  15. 15.753 + 645 =
  16. 16.227 + 177 =
  17. 17.619 + 678 =
  18. 18.528 + 449 =
  19. 19.515 + 165 =
  20. 20.293 + 173 =
  21. 21.338 + 184 =
  22. 22.652 + 538 =
  23. 23.353 + 591 =
  24. 24.787 + 376 =
  25. 25.533 + 528 =
  26. 26.645 + 194 =
  27. 27.894 − 692 =
  28. 28.867 − 172 =
  29. 29.174 + 171 =
  30. 30.807 − 332 =
  31. 31.669 − 234 =
  32. 32.179 + 491 =
  33. 33.307 + 228 =
  34. 34.934 − 267 =
  35. 35.973 − 381 =
  36. 36.513 + 484 =
  37. 37.650 − 514 =
  38. 38.239 + 176 =
  39. 39.923 − 292 =
  40. 40.129 + 607 =

Answer key

  1. 631
  2. 546
  3. 289
  4. 108
  5. 681
  6. 151
  7. 793
  8. 777
  9. 133
  10. 840
  11. 421
  12. 1060
  13. 485
  14. 545
  15. 1398
  16. 404
  17. 1297
  18. 977
  19. 680
  20. 466
  21. 522
  22. 1190
  23. 944
  24. 1163
  25. 1061
  26. 839
  27. 202
  28. 695
  29. 345
  30. 475
  31. 435
  32. 670
  33. 535
  34. 667
  35. 592
  36. 997
  37. 136
  38. 415
  39. 631
  40. 736

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