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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 30 · 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. 1.198 + 164 =
  2. 2.294 + 562 =
  3. 3.517 + 611 =
  4. 4.853 − 133 =
  5. 5.657 − 365 =
  6. 6.514 − 322 =
  7. 7.586 + 191 =
  8. 8.472 + 134 =
  9. 9.623 + 216 =
  10. 10.768 + 434 =
  11. 11.668 − 396 =
  12. 12.728 + 491 =
  13. 13.207 + 497 =
  14. 14.512 − 332 =
  15. 15.538 + 387 =
  16. 16.537 − 316 =
  17. 17.165 + 295 =
  18. 18.526 + 354 =
  19. 19.710 + 483 =
  20. 20.435 + 304 =
  21. 21.577 − 411 =
  22. 22.566 + 551 =
  23. 23.518 + 392 =
  24. 24.442 + 168 =
  25. 25.453 − 341 =
  26. 26.467 + 527 =
  27. 27.975 − 567 =
  28. 28.460 − 299 =
  29. 29.253 + 371 =
  30. 30.631 + 215 =
  31. 31.596 − 407 =
  32. 32.415 − 131 =
  33. 33.619 + 131 =
  34. 34.127 + 212 =
  35. 35.440 + 355 =
  36. 36.155 + 183 =
  37. 37.860 − 708 =
  38. 38.728 − 555 =
  39. 39.577 − 303 =
  40. 40.455 + 603 =

Answer key

  1. 362
  2. 856
  3. 1128
  4. 720
  5. 292
  6. 192
  7. 777
  8. 606
  9. 839
  10. 1202
  11. 272
  12. 1219
  13. 704
  14. 180
  15. 925
  16. 221
  17. 460
  18. 880
  19. 1193
  20. 739
  21. 166
  22. 1117
  23. 910
  24. 610
  25. 112
  26. 994
  27. 408
  28. 161
  29. 624
  30. 846
  31. 189
  32. 284
  33. 750
  34. 339
  35. 795
  36. 338
  37. 152
  38. 173
  39. 274
  40. 1058

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