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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 980 · 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. 1.494 − 182 =
  2. 2.736 − 229 =
  3. 3.838 − 595 =
  4. 4.391 + 628 =
  5. 5.897 − 705 =
  6. 6.694 + 437 =
  7. 7.432 − 266 =
  8. 8.348 + 135 =
  9. 9.591 − 405 =
  10. 10.797 − 227 =
  11. 11.559 − 135 =
  12. 12.788 + 468 =
  13. 13.449 + 251 =
  14. 14.792 − 249 =
  15. 15.678 + 354 =
  16. 16.416 − 226 =
  17. 17.216 + 662 =
  18. 18.957 − 432 =
  19. 19.167 + 261 =
  20. 20.631 + 189 =
  21. 21.453 + 176 =
  22. 22.989 − 582 =
  23. 23.491 − 308 =
  24. 24.471 + 215 =
  25. 25.371 + 437 =
  26. 26.636 − 154 =
  27. 27.598 − 453 =
  28. 28.477 + 183 =
  29. 29.227 + 194 =
  30. 30.187 + 141 =
  31. 31.729 + 171 =
  32. 32.527 + 589 =
  33. 33.560 − 145 =
  34. 34.371 + 497 =
  35. 35.294 + 223 =
  36. 36.717 − 365 =
  37. 37.648 + 441 =
  38. 38.937 − 166 =
  39. 39.504 − 266 =
  40. 40.418 − 112 =

Answer key

  1. 312
  2. 507
  3. 243
  4. 1019
  5. 192
  6. 1131
  7. 166
  8. 483
  9. 186
  10. 570
  11. 424
  12. 1256
  13. 700
  14. 543
  15. 1032
  16. 190
  17. 878
  18. 525
  19. 428
  20. 820
  21. 629
  22. 407
  23. 183
  24. 686
  25. 808
  26. 482
  27. 145
  28. 660
  29. 421
  30. 328
  31. 900
  32. 1116
  33. 415
  34. 868
  35. 517
  36. 352
  37. 1089
  38. 771
  39. 238
  40. 306

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