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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 851 · 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. 1.893 − 491 =
  2. 2.471 + 125 =
  3. 3.439 − 336 =
  4. 4.721 + 461 =
  5. 5.688 + 311 =
  6. 6.925 − 608 =
  7. 7.510 − 302 =
  8. 8.895 − 131 =
  9. 9.462 − 349 =
  10. 10.510 − 381 =
  11. 11.646 + 155 =
  12. 12.451 − 165 =
  13. 13.311 + 616 =
  14. 14.817 − 138 =
  15. 15.125 + 299 =
  16. 16.910 − 553 =
  17. 17.537 − 122 =
  18. 18.735 + 681 =
  19. 19.524 − 182 =
  20. 20.770 − 381 =
  21. 21.669 − 201 =
  22. 22.251 + 387 =
  23. 23.247 + 323 =
  24. 24.492 − 381 =
  25. 25.529 + 139 =
  26. 26.768 − 259 =
  27. 27.572 − 413 =
  28. 28.526 − 299 =
  29. 29.557 − 428 =
  30. 30.564 − 245 =
  31. 31.744 + 236 =
  32. 32.699 + 494 =
  33. 33.448 + 274 =
  34. 34.509 + 668 =
  35. 35.605 + 165 =
  36. 36.843 − 194 =
  37. 37.151 + 504 =
  38. 38.722 + 145 =
  39. 39.449 + 613 =
  40. 40.147 + 226 =

Answer key

  1. 402
  2. 596
  3. 103
  4. 1182
  5. 999
  6. 317
  7. 208
  8. 764
  9. 113
  10. 129
  11. 801
  12. 286
  13. 927
  14. 679
  15. 424
  16. 357
  17. 415
  18. 1416
  19. 342
  20. 389
  21. 468
  22. 638
  23. 570
  24. 111
  25. 668
  26. 509
  27. 159
  28. 227
  29. 129
  30. 319
  31. 980
  32. 1193
  33. 722
  34. 1177
  35. 770
  36. 649
  37. 655
  38. 867
  39. 1062
  40. 373

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