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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 430 · 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. 1.540 + 169 =
  2. 2.129 + 574 =
  3. 3.200 + 659 =
  4. 4.609 − 414 =
  5. 5.658 + 321 =
  6. 6.735 − 289 =
  7. 7.424 + 531 =
  8. 8.845 − 218 =
  9. 9.146 + 324 =
  10. 10.375 + 668 =
  11. 11.618 + 391 =
  12. 12.192 + 252 =
  13. 13.427 + 339 =
  14. 14.543 − 136 =
  15. 15.421 + 541 =
  16. 16.423 − 138 =
  17. 17.446 + 323 =
  18. 18.469 − 244 =
  19. 19.970 − 377 =
  20. 20.498 − 292 =
  21. 21.309 + 658 =
  22. 22.690 + 147 =
  23. 23.464 + 601 =
  24. 24.282 + 319 =
  25. 25.711 + 678 =
  26. 26.721 − 313 =
  27. 27.276 + 585 =
  28. 28.823 − 646 =
  29. 29.669 + 273 =
  30. 30.640 + 429 =
  31. 31.708 − 155 =
  32. 32.303 + 521 =
  33. 33.219 + 356 =
  34. 34.476 + 608 =
  35. 35.287 + 631 =
  36. 36.619 + 589 =
  37. 37.557 + 595 =
  38. 38.895 − 342 =
  39. 39.734 + 681 =
  40. 40.949 − 301 =

Answer key

  1. 709
  2. 703
  3. 859
  4. 195
  5. 979
  6. 446
  7. 955
  8. 627
  9. 470
  10. 1043
  11. 1009
  12. 444
  13. 766
  14. 407
  15. 962
  16. 285
  17. 769
  18. 225
  19. 593
  20. 206
  21. 967
  22. 837
  23. 1065
  24. 601
  25. 1389
  26. 408
  27. 861
  28. 177
  29. 942
  30. 1069
  31. 553
  32. 824
  33. 575
  34. 1084
  35. 918
  36. 1208
  37. 1152
  38. 553
  39. 1415
  40. 648

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