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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 450 · 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. 1.848 − 212 =
  2. 2.525 − 424 =
  3. 3.143 + 384 =
  4. 4.298 + 145 =
  5. 5.196 + 312 =
  6. 6.698 + 195 =
  7. 7.276 + 335 =
  8. 8.183 + 182 =
  9. 9.686 − 526 =
  10. 10.619 − 372 =
  11. 11.581 + 477 =
  12. 12.367 + 264 =
  13. 13.634 − 476 =
  14. 14.724 + 397 =
  15. 15.347 + 428 =
  16. 16.291 + 626 =
  17. 17.423 + 343 =
  18. 18.273 + 288 =
  19. 19.792 − 672 =
  20. 20.777 − 252 =
  21. 21.513 − 341 =
  22. 22.504 − 195 =
  23. 23.887 − 785 =
  24. 24.719 − 194 =
  25. 25.822 − 424 =
  26. 26.490 − 275 =
  27. 27.415 − 235 =
  28. 28.479 − 352 =
  29. 29.894 − 623 =
  30. 30.801 − 549 =
  31. 31.511 − 281 =
  32. 32.654 + 163 =
  33. 33.711 + 468 =
  34. 34.616 + 304 =
  35. 35.429 + 263 =
  36. 36.517 + 431 =
  37. 37.441 + 128 =
  38. 38.861 − 361 =
  39. 39.241 + 613 =
  40. 40.549 − 405 =

Answer key

  1. 636
  2. 101
  3. 527
  4. 443
  5. 508
  6. 893
  7. 611
  8. 365
  9. 160
  10. 247
  11. 1058
  12. 631
  13. 158
  14. 1121
  15. 775
  16. 917
  17. 766
  18. 561
  19. 120
  20. 525
  21. 172
  22. 309
  23. 102
  24. 525
  25. 398
  26. 215
  27. 180
  28. 127
  29. 271
  30. 252
  31. 230
  32. 817
  33. 1179
  34. 920
  35. 692
  36. 948
  37. 569
  38. 500
  39. 854
  40. 144

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