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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 134 · 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. 1.248 + 113 =
  2. 2.835 − 289 =
  3. 3.974 − 351 =
  4. 4.434 + 365 =
  5. 5.702 + 118 =
  6. 6.545 − 409 =
  7. 7.509 + 544 =
  8. 8.723 − 236 =
  9. 9.894 − 508 =
  10. 10.685 + 532 =
  11. 11.727 − 138 =
  12. 12.736 − 483 =
  13. 13.419 + 598 =
  14. 14.720 + 629 =
  15. 15.272 + 456 =
  16. 16.433 + 468 =
  17. 17.415 + 597 =
  18. 18.263 + 611 =
  19. 19.629 + 214 =
  20. 20.474 − 242 =
  21. 21.436 + 455 =
  22. 22.228 + 132 =
  23. 23.743 − 425 =
  24. 24.918 − 627 =
  25. 25.171 + 484 =
  26. 26.441 − 151 =
  27. 27.982 − 408 =
  28. 28.516 + 346 =
  29. 29.487 − 304 =
  30. 30.521 + 218 =
  31. 31.308 + 242 =
  32. 32.528 − 145 =
  33. 33.424 − 141 =
  34. 34.149 + 249 =
  35. 35.310 + 281 =
  36. 36.789 + 421 =
  37. 37.464 − 283 =
  38. 38.651 + 413 =
  39. 39.618 + 165 =
  40. 40.198 + 356 =

Answer key

  1. 361
  2. 546
  3. 623
  4. 799
  5. 820
  6. 136
  7. 1053
  8. 487
  9. 386
  10. 1217
  11. 589
  12. 253
  13. 1017
  14. 1349
  15. 728
  16. 901
  17. 1012
  18. 874
  19. 843
  20. 232
  21. 891
  22. 360
  23. 318
  24. 291
  25. 655
  26. 290
  27. 574
  28. 862
  29. 183
  30. 739
  31. 550
  32. 383
  33. 283
  34. 398
  35. 591
  36. 1210
  37. 181
  38. 1064
  39. 783
  40. 554

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