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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 653 · 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. 1.183 + 581 =
  2. 2.710 + 518 =
  3. 3.430 + 192 =
  4. 4.213 + 221 =
  5. 5.203 + 654 =
  6. 6.439 − 317 =
  7. 7.802 − 221 =
  8. 8.940 − 471 =
  9. 9.397 + 431 =
  10. 10.452 − 229 =
  11. 11.130 + 601 =
  12. 12.757 + 225 =
  13. 13.157 + 118 =
  14. 14.126 + 681 =
  15. 15.776 + 324 =
  16. 16.978 − 508 =
  17. 17.816 − 201 =
  18. 18.489 − 199 =
  19. 19.187 + 488 =
  20. 20.932 − 608 =
  21. 21.617 − 207 =
  22. 22.532 + 223 =
  23. 23.468 + 224 =
  24. 24.494 + 568 =
  25. 25.731 + 504 =
  26. 26.602 + 556 =
  27. 27.781 − 147 =
  28. 28.239 + 275 =
  29. 29.354 + 507 =
  30. 30.761 − 403 =
  31. 31.129 + 446 =
  32. 32.746 − 502 =
  33. 33.400 + 372 =
  34. 34.396 + 242 =
  35. 35.687 − 541 =
  36. 36.408 + 642 =
  37. 37.198 + 165 =
  38. 38.340 + 248 =
  39. 39.282 + 621 =
  40. 40.439 − 204 =

Answer key

  1. 764
  2. 1228
  3. 622
  4. 434
  5. 857
  6. 122
  7. 581
  8. 469
  9. 828
  10. 223
  11. 731
  12. 982
  13. 275
  14. 807
  15. 1100
  16. 470
  17. 615
  18. 290
  19. 675
  20. 324
  21. 410
  22. 755
  23. 692
  24. 1062
  25. 1235
  26. 1158
  27. 634
  28. 514
  29. 861
  30. 358
  31. 575
  32. 244
  33. 772
  34. 638
  35. 146
  36. 1050
  37. 363
  38. 588
  39. 903
  40. 235

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