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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 449 · 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. 1.664 + 629 =
  2. 2.215 + 333 =
  3. 3.826 − 159 =
  4. 4.638 + 116 =
  5. 5.354 + 655 =
  6. 6.573 − 294 =
  7. 7.964 − 277 =
  8. 8.616 − 428 =
  9. 9.765 + 371 =
  10. 10.466 − 131 =
  11. 11.548 + 672 =
  12. 12.361 + 301 =
  13. 13.977 − 505 =
  14. 14.308 + 141 =
  15. 15.502 − 151 =
  16. 16.123 + 198 =
  17. 17.413 + 435 =
  18. 18.951 − 128 =
  19. 19.692 + 272 =
  20. 20.655 − 165 =
  21. 21.474 − 321 =
  22. 22.382 + 688 =
  23. 23.773 + 683 =
  24. 24.722 + 583 =
  25. 25.669 − 438 =
  26. 26.438 + 145 =
  27. 27.636 − 143 =
  28. 28.971 − 491 =
  29. 29.552 + 181 =
  30. 30.869 − 371 =
  31. 31.505 + 189 =
  32. 32.927 − 544 =
  33. 33.518 − 318 =
  34. 34.745 − 191 =
  35. 35.657 + 414 =
  36. 36.451 + 612 =
  37. 37.281 + 178 =
  38. 38.641 − 371 =
  39. 39.903 − 798 =
  40. 40.393 + 476 =

Answer key

  1. 1293
  2. 548
  3. 667
  4. 754
  5. 1009
  6. 279
  7. 687
  8. 188
  9. 1136
  10. 335
  11. 1220
  12. 662
  13. 472
  14. 449
  15. 351
  16. 321
  17. 848
  18. 823
  19. 964
  20. 490
  21. 153
  22. 1070
  23. 1456
  24. 1305
  25. 231
  26. 583
  27. 493
  28. 480
  29. 733
  30. 498
  31. 694
  32. 383
  33. 200
  34. 554
  35. 1071
  36. 1063
  37. 459
  38. 270
  39. 105
  40. 869

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