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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 104 · 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. 1.908 − 501 =
  2. 2.555 + 635 =
  3. 3.564 + 235 =
  4. 4.731 + 606 =
  5. 5.211 + 561 =
  6. 6.222 + 635 =
  7. 7.482 − 371 =
  8. 8.864 − 623 =
  9. 9.878 − 404 =
  10. 10.617 − 371 =
  11. 11.511 + 251 =
  12. 12.733 + 568 =
  13. 13.288 + 687 =
  14. 14.213 + 455 =
  15. 15.501 − 348 =
  16. 16.521 + 612 =
  17. 17.910 − 724 =
  18. 18.461 + 494 =
  19. 19.463 − 134 =
  20. 20.203 + 352 =
  21. 21.525 − 301 =
  22. 22.791 − 589 =
  23. 23.180 + 513 =
  24. 24.697 + 461 =
  25. 25.203 + 246 =
  26. 26.557 − 285 =
  27. 27.568 + 603 =
  28. 28.717 − 477 =
  29. 29.654 + 541 =
  30. 30.560 + 368 =
  31. 31.362 + 365 =
  32. 32.913 − 368 =
  33. 33.742 − 167 =
  34. 34.308 + 238 =
  35. 35.616 + 647 =
  36. 36.863 − 718 =
  37. 37.647 − 452 =
  38. 38.329 + 136 =
  39. 39.444 + 484 =
  40. 40.517 + 149 =

Answer key

  1. 407
  2. 1190
  3. 799
  4. 1337
  5. 772
  6. 857
  7. 111
  8. 241
  9. 474
  10. 246
  11. 762
  12. 1301
  13. 975
  14. 668
  15. 153
  16. 1133
  17. 186
  18. 955
  19. 329
  20. 555
  21. 224
  22. 202
  23. 693
  24. 1158
  25. 449
  26. 272
  27. 1171
  28. 240
  29. 1195
  30. 928
  31. 727
  32. 545
  33. 575
  34. 546
  35. 1263
  36. 145
  37. 195
  38. 465
  39. 928
  40. 666

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