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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 721 · 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. 1.687 − 205 =
  2. 2.761 + 385 =
  3. 3.757 + 661 =
  4. 4.238 + 497 =
  5. 5.229 + 633 =
  6. 6.790 − 506 =
  7. 7.450 + 222 =
  8. 8.852 − 509 =
  9. 9.777 + 505 =
  10. 10.627 − 187 =
  11. 11.591 − 206 =
  12. 12.372 + 601 =
  13. 13.453 + 673 =
  14. 14.340 + 153 =
  15. 15.611 − 148 =
  16. 16.530 − 295 =
  17. 17.296 + 278 =
  18. 18.740 + 276 =
  19. 19.162 + 356 =
  20. 20.424 − 256 =
  21. 21.330 + 205 =
  22. 22.745 + 241 =
  23. 23.250 + 601 =
  24. 24.312 + 583 =
  25. 25.466 − 303 =
  26. 26.321 + 275 =
  27. 27.411 + 611 =
  28. 28.431 + 341 =
  29. 29.565 − 461 =
  30. 30.738 − 436 =
  31. 31.772 + 286 =
  32. 32.787 − 467 =
  33. 33.369 + 633 =
  34. 34.159 + 352 =
  35. 35.973 − 225 =
  36. 36.882 − 508 =
  37. 37.602 − 194 =
  38. 38.183 + 378 =
  39. 39.630 + 305 =
  40. 40.457 − 129 =

Answer key

  1. 482
  2. 1146
  3. 1418
  4. 735
  5. 862
  6. 284
  7. 672
  8. 343
  9. 1282
  10. 440
  11. 385
  12. 973
  13. 1126
  14. 493
  15. 463
  16. 235
  17. 574
  18. 1016
  19. 518
  20. 168
  21. 535
  22. 986
  23. 851
  24. 895
  25. 163
  26. 596
  27. 1022
  28. 772
  29. 104
  30. 302
  31. 1058
  32. 320
  33. 1002
  34. 511
  35. 748
  36. 374
  37. 408
  38. 561
  39. 935
  40. 328

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