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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 186 · 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. 1.974 − 191 =
  2. 2.477 + 641 =
  3. 3.472 − 261 =
  4. 4.764 + 346 =
  5. 5.293 + 667 =
  6. 6.415 − 165 =
  7. 7.827 − 196 =
  8. 8.773 + 491 =
  9. 9.634 − 374 =
  10. 10.683 − 457 =
  11. 11.432 + 591 =
  12. 12.584 + 257 =
  13. 13.877 − 679 =
  14. 14.315 + 199 =
  15. 15.955 − 153 =
  16. 16.679 − 156 =
  17. 17.489 − 273 =
  18. 18.713 − 261 =
  19. 19.705 − 478 =
  20. 20.152 + 184 =
  21. 21.138 + 687 =
  22. 22.575 + 427 =
  23. 23.354 + 246 =
  24. 24.282 + 654 =
  25. 25.492 + 548 =
  26. 26.871 − 693 =
  27. 27.529 − 383 =
  28. 28.472 + 206 =
  29. 29.487 − 129 =
  30. 30.984 − 211 =
  31. 31.510 − 366 =
  32. 32.432 − 188 =
  33. 33.656 + 452 =
  34. 34.444 + 675 =
  35. 35.126 + 662 =
  36. 36.780 + 519 =
  37. 37.633 − 445 =
  38. 38.657 + 522 =
  39. 39.267 + 391 =
  40. 40.784 + 311 =

Answer key

  1. 783
  2. 1118
  3. 211
  4. 1110
  5. 960
  6. 250
  7. 631
  8. 1264
  9. 260
  10. 226
  11. 1023
  12. 841
  13. 198
  14. 514
  15. 802
  16. 523
  17. 216
  18. 452
  19. 227
  20. 336
  21. 825
  22. 1002
  23. 600
  24. 936
  25. 1040
  26. 178
  27. 146
  28. 678
  29. 358
  30. 773
  31. 144
  32. 244
  33. 1108
  34. 1119
  35. 788
  36. 1299
  37. 188
  38. 1179
  39. 658
  40. 1095

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