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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 567 · 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. 1.181 + 267 =
  2. 2.782 − 143 =
  3. 3.429 + 287 =
  4. 4.372 + 499 =
  5. 5.515 + 244 =
  6. 6.602 − 481 =
  7. 7.136 + 432 =
  8. 8.782 + 171 =
  9. 9.430 + 158 =
  10. 10.682 − 161 =
  11. 11.204 + 218 =
  12. 12.887 − 787 =
  13. 13.572 − 127 =
  14. 14.811 − 559 =
  15. 15.666 − 225 =
  16. 16.425 − 281 =
  17. 17.442 + 584 =
  18. 18.152 + 255 =
  19. 19.281 + 167 =
  20. 20.280 + 231 =
  21. 21.454 − 245 =
  22. 22.522 + 126 =
  23. 23.277 + 231 =
  24. 24.638 − 423 =
  25. 25.754 + 601 =
  26. 26.839 − 281 =
  27. 27.400 + 625 =
  28. 28.888 − 196 =
  29. 29.675 + 313 =
  30. 30.725 + 275 =
  31. 31.214 + 266 =
  32. 32.186 + 399 =
  33. 33.652 − 248 =
  34. 34.708 − 572 =
  35. 35.467 − 232 =
  36. 36.544 + 414 =
  37. 37.835 − 537 =
  38. 38.538 + 341 =
  39. 39.723 − 521 =
  40. 40.907 − 723 =

Answer key

  1. 448
  2. 639
  3. 716
  4. 871
  5. 759
  6. 121
  7. 568
  8. 953
  9. 588
  10. 521
  11. 422
  12. 100
  13. 445
  14. 252
  15. 441
  16. 144
  17. 1026
  18. 407
  19. 448
  20. 511
  21. 209
  22. 648
  23. 508
  24. 215
  25. 1355
  26. 558
  27. 1025
  28. 692
  29. 988
  30. 1000
  31. 480
  32. 585
  33. 404
  34. 136
  35. 235
  36. 958
  37. 298
  38. 879
  39. 202
  40. 184

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