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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 702 · 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. 1.419 + 352 =
  2. 2.941 − 239 =
  3. 3.236 + 153 =
  4. 4.724 − 446 =
  5. 5.540 + 537 =
  6. 6.312 + 397 =
  7. 7.629 + 499 =
  8. 8.565 + 284 =
  9. 9.723 − 499 =
  10. 10.676 − 115 =
  11. 11.404 + 187 =
  12. 12.534 − 347 =
  13. 13.905 − 351 =
  14. 14.909 − 716 =
  15. 15.775 + 429 =
  16. 16.273 + 186 =
  17. 17.252 + 236 =
  18. 18.184 + 538 =
  19. 19.629 − 173 =
  20. 20.511 − 221 =
  21. 21.851 − 667 =
  22. 22.786 − 232 =
  23. 23.795 − 137 =
  24. 24.623 − 473 =
  25. 25.697 − 496 =
  26. 26.633 + 121 =
  27. 27.814 − 332 =
  28. 28.616 − 271 =
  29. 29.806 − 251 =
  30. 30.328 + 124 =
  31. 31.507 − 398 =
  32. 32.821 − 717 =
  33. 33.636 + 115 =
  34. 34.546 + 589 =
  35. 35.571 − 123 =
  36. 36.490 − 114 =
  37. 37.922 − 208 =
  38. 38.536 + 606 =
  39. 39.383 + 162 =
  40. 40.865 − 244 =

Answer key

  1. 771
  2. 702
  3. 389
  4. 278
  5. 1077
  6. 709
  7. 1128
  8. 849
  9. 224
  10. 561
  11. 591
  12. 187
  13. 554
  14. 193
  15. 1204
  16. 459
  17. 488
  18. 722
  19. 456
  20. 290
  21. 184
  22. 554
  23. 658
  24. 150
  25. 201
  26. 754
  27. 482
  28. 345
  29. 555
  30. 452
  31. 109
  32. 104
  33. 751
  34. 1135
  35. 448
  36. 376
  37. 714
  38. 1142
  39. 545
  40. 621

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