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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 317 · 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. 1.846 − 631 =
  2. 2.542 − 377 =
  3. 3.276 + 231 =
  4. 4.668 − 515 =
  5. 5.281 + 187 =
  6. 6.399 + 483 =
  7. 7.540 − 206 =
  8. 8.419 − 169 =
  9. 9.866 − 716 =
  10. 10.886 − 752 =
  11. 11.499 − 303 =
  12. 12.460 − 255 =
  13. 13.572 + 153 =
  14. 14.649 − 493 =
  15. 15.646 + 648 =
  16. 16.592 + 504 =
  17. 17.501 − 152 =
  18. 18.695 + 514 =
  19. 19.366 + 279 =
  20. 20.881 − 177 =
  21. 21.576 + 414 =
  22. 22.732 − 165 =
  23. 23.551 − 242 =
  24. 24.513 + 527 =
  25. 25.548 + 461 =
  26. 26.279 + 116 =
  27. 27.531 + 386 =
  28. 28.694 + 466 =
  29. 29.276 + 124 =
  30. 30.526 − 282 =
  31. 31.431 + 112 =
  32. 32.569 − 388 =
  33. 33.905 − 566 =
  34. 34.723 + 428 =
  35. 35.495 − 171 =
  36. 36.548 − 352 =
  37. 37.188 + 125 =
  38. 38.233 + 441 =
  39. 39.144 + 122 =
  40. 40.468 − 208 =

Answer key

  1. 215
  2. 165
  3. 507
  4. 153
  5. 468
  6. 882
  7. 334
  8. 250
  9. 150
  10. 134
  11. 196
  12. 205
  13. 725
  14. 156
  15. 1294
  16. 1096
  17. 349
  18. 1209
  19. 645
  20. 704
  21. 990
  22. 567
  23. 309
  24. 1040
  25. 1009
  26. 395
  27. 917
  28. 1160
  29. 400
  30. 244
  31. 543
  32. 181
  33. 339
  34. 1151
  35. 324
  36. 196
  37. 313
  38. 674
  39. 266
  40. 260

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