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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 273 · 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. 1.630 − 213 =
  2. 2.695 + 182 =
  3. 3.795 − 322 =
  4. 4.260 + 453 =
  5. 5.259 + 131 =
  6. 6.872 − 705 =
  7. 7.877 − 628 =
  8. 8.607 − 282 =
  9. 9.560 + 478 =
  10. 10.597 + 449 =
  11. 11.575 − 237 =
  12. 12.234 + 431 =
  13. 13.225 + 225 =
  14. 14.186 + 523 =
  15. 15.342 + 399 =
  16. 16.939 − 582 =
  17. 17.631 + 684 =
  18. 18.615 + 473 =
  19. 19.988 − 842 =
  20. 20.609 + 412 =
  21. 21.624 + 607 =
  22. 22.158 + 218 =
  23. 23.190 + 432 =
  24. 24.442 + 156 =
  25. 25.824 − 171 =
  26. 26.510 − 163 =
  27. 27.786 + 537 =
  28. 28.206 + 364 =
  29. 29.606 + 407 =
  30. 30.893 − 364 =
  31. 31.758 + 588 =
  32. 32.303 + 328 =
  33. 33.254 + 439 =
  34. 34.621 − 359 =
  35. 35.741 + 477 =
  36. 36.978 − 138 =
  37. 37.348 + 315 =
  38. 38.680 + 435 =
  39. 39.560 − 341 =
  40. 40.544 + 341 =

Answer key

  1. 417
  2. 877
  3. 473
  4. 713
  5. 390
  6. 167
  7. 249
  8. 325
  9. 1038
  10. 1046
  11. 338
  12. 665
  13. 450
  14. 709
  15. 741
  16. 357
  17. 1315
  18. 1088
  19. 146
  20. 1021
  21. 1231
  22. 376
  23. 622
  24. 598
  25. 653
  26. 347
  27. 1323
  28. 570
  29. 1013
  30. 529
  31. 1346
  32. 631
  33. 693
  34. 262
  35. 1218
  36. 840
  37. 663
  38. 1115
  39. 219
  40. 885

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