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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 671 · 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. 1.523 + 513 =
  2. 2.767 − 302 =
  3. 3.679 − 261 =
  4. 4.387 + 543 =
  5. 5.865 − 693 =
  6. 6.176 + 607 =
  7. 7.528 − 372 =
  8. 8.552 − 364 =
  9. 9.819 − 531 =
  10. 10.865 − 217 =
  11. 11.636 − 187 =
  12. 12.201 + 445 =
  13. 13.836 − 426 =
  14. 14.733 + 552 =
  15. 15.176 + 295 =
  16. 16.926 − 121 =
  17. 17.867 − 745 =
  18. 18.317 + 594 =
  19. 19.956 − 251 =
  20. 20.928 − 306 =
  21. 21.768 − 227 =
  22. 22.452 + 138 =
  23. 23.251 + 208 =
  24. 24.402 + 619 =
  25. 25.508 + 395 =
  26. 26.246 + 561 =
  27. 27.166 + 241 =
  28. 28.504 + 519 =
  29. 29.665 − 391 =
  30. 30.351 + 509 =
  31. 31.621 + 204 =
  32. 32.515 − 289 =
  33. 33.769 + 115 =
  34. 34.500 − 133 =
  35. 35.741 − 128 =
  36. 36.892 − 462 =
  37. 37.613 − 339 =
  38. 38.185 + 546 =
  39. 39.216 + 455 =
  40. 40.260 + 212 =

Answer key

  1. 1036
  2. 465
  3. 418
  4. 930
  5. 172
  6. 783
  7. 156
  8. 188
  9. 288
  10. 648
  11. 449
  12. 646
  13. 410
  14. 1285
  15. 471
  16. 805
  17. 122
  18. 911
  19. 705
  20. 622
  21. 541
  22. 590
  23. 459
  24. 1021
  25. 903
  26. 807
  27. 407
  28. 1023
  29. 274
  30. 860
  31. 825
  32. 226
  33. 884
  34. 367
  35. 613
  36. 430
  37. 274
  38. 731
  39. 671
  40. 472

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