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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 697 · 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. 1.708 − 555 =
  2. 2.447 + 423 =
  3. 3.266 + 387 =
  4. 4.909 − 406 =
  5. 5.897 − 532 =
  6. 6.369 + 538 =
  7. 7.620 − 229 =
  8. 8.198 + 368 =
  9. 9.663 − 112 =
  10. 10.607 + 476 =
  11. 11.981 − 793 =
  12. 12.258 + 321 =
  13. 13.772 − 241 =
  14. 14.362 + 211 =
  15. 15.248 + 344 =
  16. 16.240 + 661 =
  17. 17.591 − 348 =
  18. 18.171 + 652 =
  19. 19.843 − 261 =
  20. 20.382 + 161 =
  21. 21.863 − 553 =
  22. 22.148 + 568 =
  23. 23.577 + 259 =
  24. 24.577 + 278 =
  25. 25.369 + 367 =
  26. 26.621 − 176 =
  27. 27.441 − 292 =
  28. 28.289 + 611 =
  29. 29.429 + 127 =
  30. 30.669 − 163 =
  31. 31.745 − 227 =
  32. 32.131 + 282 =
  33. 33.194 + 678 =
  34. 34.598 − 143 =
  35. 35.439 + 598 =
  36. 36.864 − 232 =
  37. 37.573 − 379 =
  38. 38.873 − 173 =
  39. 39.484 + 266 =
  40. 40.137 + 181 =

Answer key

  1. 153
  2. 870
  3. 653
  4. 503
  5. 365
  6. 907
  7. 391
  8. 566
  9. 551
  10. 1083
  11. 188
  12. 579
  13. 531
  14. 573
  15. 592
  16. 901
  17. 243
  18. 823
  19. 582
  20. 543
  21. 310
  22. 716
  23. 836
  24. 855
  25. 736
  26. 445
  27. 149
  28. 900
  29. 556
  30. 506
  31. 518
  32. 413
  33. 872
  34. 455
  35. 1037
  36. 632
  37. 194
  38. 700
  39. 750
  40. 318

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