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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 573 · 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. 1.358 + 481 =
  2. 2.296 + 644 =
  3. 3.762 + 259 =
  4. 4.424 − 232 =
  5. 5.621 + 468 =
  6. 6.322 + 133 =
  7. 7.796 − 199 =
  8. 8.187 + 331 =
  9. 9.832 − 606 =
  10. 10.647 + 589 =
  11. 11.739 + 491 =
  12. 12.434 − 201 =
  13. 13.287 + 649 =
  14. 14.754 − 253 =
  15. 15.429 − 252 =
  16. 16.638 + 363 =
  17. 17.407 + 389 =
  18. 18.704 − 115 =
  19. 19.873 − 241 =
  20. 20.248 + 164 =
  21. 21.580 + 586 =
  22. 22.702 − 146 =
  23. 23.490 + 466 =
  24. 24.278 + 559 =
  25. 25.719 − 131 =
  26. 26.219 + 541 =
  27. 27.870 − 738 =
  28. 28.599 + 215 =
  29. 29.496 − 376 =
  30. 30.303 + 121 =
  31. 31.268 + 531 =
  32. 32.468 − 158 =
  33. 33.473 − 297 =
  34. 34.747 − 141 =
  35. 35.422 − 146 =
  36. 36.505 + 118 =
  37. 37.512 − 175 =
  38. 38.971 − 571 =
  39. 39.536 − 201 =
  40. 40.603 + 192 =

Answer key

  1. 839
  2. 940
  3. 1021
  4. 192
  5. 1089
  6. 455
  7. 597
  8. 518
  9. 226
  10. 1236
  11. 1230
  12. 233
  13. 936
  14. 501
  15. 177
  16. 1001
  17. 796
  18. 589
  19. 632
  20. 412
  21. 1166
  22. 556
  23. 956
  24. 837
  25. 588
  26. 760
  27. 132
  28. 814
  29. 120
  30. 424
  31. 799
  32. 310
  33. 176
  34. 606
  35. 276
  36. 623
  37. 337
  38. 400
  39. 335
  40. 795

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