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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 680 · 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. 1.146 + 687 =
  2. 2.559 + 274 =
  3. 3.752 + 611 =
  4. 4.419 + 641 =
  5. 5.208 + 566 =
  6. 6.453 + 344 =
  7. 7.536 + 171 =
  8. 8.484 − 371 =
  9. 9.561 − 333 =
  10. 10.465 + 597 =
  11. 11.907 − 485 =
  12. 12.397 + 222 =
  13. 13.826 − 195 =
  14. 14.502 + 169 =
  15. 15.299 + 229 =
  16. 16.596 + 311 =
  17. 17.482 − 306 =
  18. 18.537 − 145 =
  19. 19.492 + 614 =
  20. 20.175 + 501 =
  21. 21.446 + 347 =
  22. 22.638 − 517 =
  23. 23.728 + 188 =
  24. 24.782 − 679 =
  25. 25.613 − 171 =
  26. 26.606 − 311 =
  27. 27.821 − 422 =
  28. 28.547 − 208 =
  29. 29.588 + 395 =
  30. 30.773 − 567 =
  31. 31.641 − 116 =
  32. 32.508 − 179 =
  33. 33.666 + 334 =
  34. 34.460 + 215 =
  35. 35.513 + 271 =
  36. 36.134 + 243 =
  37. 37.416 + 348 =
  38. 38.661 + 155 =
  39. 39.936 − 225 =
  40. 40.143 + 348 =

Answer key

  1. 833
  2. 833
  3. 1363
  4. 1060
  5. 774
  6. 797
  7. 707
  8. 113
  9. 228
  10. 1062
  11. 422
  12. 619
  13. 631
  14. 671
  15. 528
  16. 907
  17. 176
  18. 392
  19. 1106
  20. 676
  21. 793
  22. 121
  23. 916
  24. 103
  25. 442
  26. 295
  27. 399
  28. 339
  29. 983
  30. 206
  31. 525
  32. 329
  33. 1000
  34. 675
  35. 784
  36. 377
  37. 764
  38. 816
  39. 711
  40. 491

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