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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 214 · 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. 1.505 − 223 =
  2. 2.628 − 152 =
  3. 3.219 + 307 =
  4. 4.698 − 204 =
  5. 5.765 + 141 =
  6. 6.762 − 331 =
  7. 7.361 + 227 =
  8. 8.551 + 355 =
  9. 9.378 + 273 =
  10. 10.920 − 473 =
  11. 11.780 + 268 =
  12. 12.214 + 316 =
  13. 13.571 − 147 =
  14. 14.526 + 592 =
  15. 15.589 + 517 =
  16. 16.595 − 286 =
  17. 17.225 + 387 =
  18. 18.224 + 369 =
  19. 19.751 + 655 =
  20. 20.964 − 273 =
  21. 21.700 − 158 =
  22. 22.505 + 419 =
  23. 23.457 − 179 =
  24. 24.930 − 391 =
  25. 25.418 − 133 =
  26. 26.559 + 472 =
  27. 27.123 + 221 =
  28. 28.171 + 608 =
  29. 29.690 + 431 =
  30. 30.142 + 295 =
  31. 31.448 − 251 =
  32. 32.589 + 368 =
  33. 33.751 + 472 =
  34. 34.477 − 234 =
  35. 35.555 − 174 =
  36. 36.658 − 419 =
  37. 37.809 − 621 =
  38. 38.160 + 198 =
  39. 39.640 + 372 =
  40. 40.287 + 173 =

Answer key

  1. 282
  2. 476
  3. 526
  4. 494
  5. 906
  6. 431
  7. 588
  8. 906
  9. 651
  10. 447
  11. 1048
  12. 530
  13. 424
  14. 1118
  15. 1106
  16. 309
  17. 612
  18. 593
  19. 1406
  20. 691
  21. 542
  22. 924
  23. 278
  24. 539
  25. 285
  26. 1031
  27. 344
  28. 779
  29. 1121
  30. 437
  31. 197
  32. 957
  33. 1223
  34. 243
  35. 381
  36. 239
  37. 188
  38. 358
  39. 1012
  40. 460

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