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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 772 · 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. 1.893 − 586 =
  2. 2.566 + 116 =
  3. 3.635 + 263 =
  4. 4.542 − 319 =
  5. 5.846 − 584 =
  6. 6.973 − 661 =
  7. 7.647 − 245 =
  8. 8.666 + 373 =
  9. 9.619 − 286 =
  10. 10.185 + 182 =
  11. 11.697 − 231 =
  12. 12.580 + 485 =
  13. 13.303 + 277 =
  14. 14.481 − 113 =
  15. 15.510 + 124 =
  16. 16.519 − 229 =
  17. 17.460 + 536 =
  18. 18.552 + 213 =
  19. 19.735 − 207 =
  20. 20.191 + 546 =
  21. 21.707 + 148 =
  22. 22.448 − 234 =
  23. 23.179 + 472 =
  24. 24.251 + 504 =
  25. 25.724 − 136 =
  26. 26.624 + 374 =
  27. 27.583 − 241 =
  28. 28.703 − 542 =
  29. 29.397 + 455 =
  30. 30.487 − 321 =
  31. 31.632 + 646 =
  32. 32.485 + 142 =
  33. 33.638 − 444 =
  34. 34.246 + 479 =
  35. 35.803 − 496 =
  36. 36.634 − 302 =
  37. 37.806 − 198 =
  38. 38.890 − 332 =
  39. 39.595 + 556 =
  40. 40.813 − 234 =

Answer key

  1. 307
  2. 682
  3. 898
  4. 223
  5. 262
  6. 312
  7. 402
  8. 1039
  9. 333
  10. 367
  11. 466
  12. 1065
  13. 580
  14. 368
  15. 634
  16. 290
  17. 996
  18. 765
  19. 528
  20. 737
  21. 855
  22. 214
  23. 651
  24. 755
  25. 588
  26. 998
  27. 342
  28. 161
  29. 852
  30. 166
  31. 1278
  32. 627
  33. 194
  34. 725
  35. 307
  36. 332
  37. 608
  38. 558
  39. 1151
  40. 579

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