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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 881 · 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. 1.674 + 135 =
  2. 2.887 − 331 =
  3. 3.410 + 673 =
  4. 4.592 + 216 =
  5. 5.944 − 128 =
  6. 6.643 − 211 =
  7. 7.730 − 566 =
  8. 8.517 + 483 =
  9. 9.281 + 465 =
  10. 10.432 + 433 =
  11. 11.238 + 583 =
  12. 12.160 + 528 =
  13. 13.395 + 349 =
  14. 14.587 − 149 =
  15. 15.593 − 229 =
  16. 16.174 + 177 =
  17. 17.604 + 606 =
  18. 18.628 + 494 =
  19. 19.815 − 418 =
  20. 20.381 + 568 =
  21. 21.513 + 121 =
  22. 22.129 + 284 =
  23. 23.573 + 146 =
  24. 24.765 + 354 =
  25. 25.534 + 525 =
  26. 26.152 + 619 =
  27. 27.463 − 269 =
  28. 28.135 + 241 =
  29. 29.625 − 182 =
  30. 30.561 − 416 =
  31. 31.784 + 439 =
  32. 32.274 + 308 =
  33. 33.550 + 249 =
  34. 34.837 − 366 =
  35. 35.666 + 374 =
  36. 36.606 − 365 =
  37. 37.686 + 618 =
  38. 38.879 − 233 =
  39. 39.419 + 344 =
  40. 40.457 + 381 =

Answer key

  1. 809
  2. 556
  3. 1083
  4. 808
  5. 816
  6. 432
  7. 164
  8. 1000
  9. 746
  10. 865
  11. 821
  12. 688
  13. 744
  14. 438
  15. 364
  16. 351
  17. 1210
  18. 1122
  19. 397
  20. 949
  21. 634
  22. 413
  23. 719
  24. 1119
  25. 1059
  26. 771
  27. 194
  28. 376
  29. 443
  30. 145
  31. 1223
  32. 582
  33. 799
  34. 471
  35. 1040
  36. 241
  37. 1304
  38. 646
  39. 763
  40. 838

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