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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 102 · 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. 1.340 + 374 =
  2. 2.180 + 301 =
  3. 3.509 + 433 =
  4. 4.135 + 395 =
  5. 5.925 − 461 =
  6. 6.744 + 675 =
  7. 7.744 + 324 =
  8. 8.577 − 452 =
  9. 9.151 + 321 =
  10. 10.441 − 161 =
  11. 11.976 − 745 =
  12. 12.927 − 599 =
  13. 13.728 + 325 =
  14. 14.895 − 722 =
  15. 15.750 + 493 =
  16. 16.159 + 304 =
  17. 17.433 + 681 =
  18. 18.643 + 177 =
  19. 19.926 − 214 =
  20. 20.844 − 442 =
  21. 21.242 + 142 =
  22. 22.132 + 661 =
  23. 23.720 − 586 =
  24. 24.711 + 463 =
  25. 25.900 − 414 =
  26. 26.516 + 671 =
  27. 27.961 − 747 =
  28. 28.688 − 174 =
  29. 29.689 + 509 =
  30. 30.509 + 506 =
  31. 31.533 + 462 =
  32. 32.639 − 356 =
  33. 33.212 + 282 =
  34. 34.932 − 441 =
  35. 35.197 + 567 =
  36. 36.468 − 113 =
  37. 37.794 − 268 =
  38. 38.796 − 673 =
  39. 39.465 − 211 =
  40. 40.428 + 243 =

Answer key

  1. 714
  2. 481
  3. 942
  4. 530
  5. 464
  6. 1419
  7. 1068
  8. 125
  9. 472
  10. 280
  11. 231
  12. 328
  13. 1053
  14. 173
  15. 1243
  16. 463
  17. 1114
  18. 820
  19. 712
  20. 402
  21. 384
  22. 793
  23. 134
  24. 1174
  25. 486
  26. 1187
  27. 214
  28. 514
  29. 1198
  30. 1015
  31. 995
  32. 283
  33. 494
  34. 491
  35. 764
  36. 355
  37. 526
  38. 123
  39. 254
  40. 671

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