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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 508 · 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. 1.810 − 147 =
  2. 2.231 + 174 =
  3. 3.642 + 363 =
  4. 4.728 + 306 =
  5. 5.660 − 372 =
  6. 6.967 − 368 =
  7. 7.645 + 142 =
  8. 8.979 − 281 =
  9. 9.151 + 166 =
  10. 10.777 − 524 =
  11. 11.854 − 625 =
  12. 12.657 + 571 =
  13. 13.473 − 313 =
  14. 14.380 + 491 =
  15. 15.494 + 499 =
  16. 16.148 + 483 =
  17. 17.572 − 413 =
  18. 18.447 − 345 =
  19. 19.140 + 491 =
  20. 20.494 − 307 =
  21. 21.223 + 165 =
  22. 22.138 + 246 =
  23. 23.436 + 311 =
  24. 24.728 + 133 =
  25. 25.374 + 332 =
  26. 26.490 + 431 =
  27. 27.170 + 265 =
  28. 28.567 + 589 =
  29. 29.577 − 131 =
  30. 30.493 − 298 =
  31. 31.581 − 418 =
  32. 32.603 + 211 =
  33. 33.720 + 172 =
  34. 34.958 − 801 =
  35. 35.166 + 118 =
  36. 36.513 − 293 =
  37. 37.388 + 157 =
  38. 38.582 − 437 =
  39. 39.775 − 131 =
  40. 40.765 − 527 =

Answer key

  1. 663
  2. 405
  3. 1005
  4. 1034
  5. 288
  6. 599
  7. 787
  8. 698
  9. 317
  10. 253
  11. 229
  12. 1228
  13. 160
  14. 871
  15. 993
  16. 631
  17. 159
  18. 102
  19. 631
  20. 187
  21. 388
  22. 384
  23. 747
  24. 861
  25. 706
  26. 921
  27. 435
  28. 1156
  29. 446
  30. 195
  31. 163
  32. 814
  33. 892
  34. 157
  35. 284
  36. 220
  37. 545
  38. 145
  39. 644
  40. 238

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