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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 578 · 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. 1.447 − 196 =
  2. 2.417 + 456 =
  3. 3.859 − 577 =
  4. 4.504 − 202 =
  5. 5.459 − 208 =
  6. 6.278 + 244 =
  7. 7.621 − 201 =
  8. 8.733 − 623 =
  9. 9.453 − 162 =
  10. 10.492 − 334 =
  11. 11.431 + 294 =
  12. 12.474 − 371 =
  13. 13.487 − 252 =
  14. 14.811 − 593 =
  15. 15.504 − 233 =
  16. 16.419 + 141 =
  17. 17.256 + 351 =
  18. 18.467 + 127 =
  19. 19.678 − 141 =
  20. 20.176 + 293 =
  21. 21.517 + 315 =
  22. 22.475 + 466 =
  23. 23.592 + 254 =
  24. 24.603 + 649 =
  25. 25.297 + 449 =
  26. 26.509 + 673 =
  27. 27.504 + 675 =
  28. 28.634 + 379 =
  29. 29.689 + 221 =
  30. 30.640 + 531 =
  31. 31.222 + 305 =
  32. 32.689 − 501 =
  33. 33.465 − 302 =
  34. 34.621 + 672 =
  35. 35.539 − 437 =
  36. 36.765 − 135 =
  37. 37.673 + 195 =
  38. 38.634 − 487 =
  39. 39.710 − 215 =
  40. 40.613 + 582 =

Answer key

  1. 251
  2. 873
  3. 282
  4. 302
  5. 251
  6. 522
  7. 420
  8. 110
  9. 291
  10. 158
  11. 725
  12. 103
  13. 235
  14. 218
  15. 271
  16. 560
  17. 607
  18. 594
  19. 537
  20. 469
  21. 832
  22. 941
  23. 846
  24. 1252
  25. 746
  26. 1182
  27. 1179
  28. 1013
  29. 910
  30. 1171
  31. 527
  32. 188
  33. 163
  34. 1293
  35. 102
  36. 630
  37. 868
  38. 147
  39. 495
  40. 1195

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