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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 357 · 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. 1.293 + 332 =
  2. 2.696 − 121 =
  3. 3.861 − 388 =
  4. 4.958 − 292 =
  5. 5.345 + 546 =
  6. 6.653 − 276 =
  7. 7.480 + 239 =
  8. 8.764 − 148 =
  9. 9.926 − 531 =
  10. 10.923 − 595 =
  11. 11.844 − 491 =
  12. 12.799 − 323 =
  13. 13.157 + 252 =
  14. 14.654 − 301 =
  15. 15.518 − 238 =
  16. 16.474 − 126 =
  17. 17.170 + 623 =
  18. 18.383 + 682 =
  19. 19.418 + 151 =
  20. 20.753 + 354 =
  21. 21.791 − 124 =
  22. 22.277 + 511 =
  23. 23.278 + 248 =
  24. 24.643 + 231 =
  25. 25.648 − 363 =
  26. 26.472 − 122 =
  27. 27.594 − 202 =
  28. 28.489 − 249 =
  29. 29.694 − 452 =
  30. 30.301 + 464 =
  31. 31.771 + 451 =
  32. 32.921 − 382 =
  33. 33.820 − 156 =
  34. 34.222 + 521 =
  35. 35.777 + 178 =
  36. 36.784 − 271 =
  37. 37.593 + 323 =
  38. 38.644 + 121 =
  39. 39.574 + 181 =
  40. 40.581 + 626 =

Answer key

  1. 625
  2. 575
  3. 473
  4. 666
  5. 891
  6. 377
  7. 719
  8. 616
  9. 395
  10. 328
  11. 353
  12. 476
  13. 409
  14. 353
  15. 280
  16. 348
  17. 793
  18. 1065
  19. 569
  20. 1107
  21. 667
  22. 788
  23. 526
  24. 874
  25. 285
  26. 350
  27. 392
  28. 240
  29. 242
  30. 765
  31. 1222
  32. 539
  33. 664
  34. 743
  35. 955
  36. 513
  37. 916
  38. 765
  39. 755
  40. 1207

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