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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 322 · 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. 1.477 + 544 =
  2. 2.703 − 123 =
  3. 3.146 + 227 =
  4. 4.655 + 163 =
  5. 5.817 − 498 =
  6. 6.434 + 652 =
  7. 7.577 + 689 =
  8. 8.138 + 399 =
  9. 9.897 − 465 =
  10. 10.770 − 121 =
  11. 11.548 + 124 =
  12. 12.639 − 241 =
  13. 13.614 + 541 =
  14. 14.861 − 481 =
  15. 15.472 + 474 =
  16. 16.438 − 338 =
  17. 17.205 + 186 =
  18. 18.573 + 366 =
  19. 19.861 − 333 =
  20. 20.573 + 175 =
  21. 21.297 + 181 =
  22. 22.425 + 176 =
  23. 23.542 − 289 =
  24. 24.514 − 137 =
  25. 25.509 − 237 =
  26. 26.745 + 561 =
  27. 27.715 + 131 =
  28. 28.874 − 613 =
  29. 29.607 − 492 =
  30. 30.559 − 326 =
  31. 31.724 − 583 =
  32. 32.410 + 405 =
  33. 33.228 + 302 =
  34. 34.967 − 289 =
  35. 35.139 + 546 =
  36. 36.163 + 514 =
  37. 37.285 + 237 =
  38. 38.603 − 395 =
  39. 39.986 − 371 =
  40. 40.577 + 451 =

Answer key

  1. 1021
  2. 580
  3. 373
  4. 818
  5. 319
  6. 1086
  7. 1266
  8. 537
  9. 432
  10. 649
  11. 672
  12. 398
  13. 1155
  14. 380
  15. 946
  16. 100
  17. 391
  18. 939
  19. 528
  20. 748
  21. 478
  22. 601
  23. 253
  24. 377
  25. 272
  26. 1306
  27. 846
  28. 261
  29. 115
  30. 233
  31. 141
  32. 815
  33. 530
  34. 678
  35. 685
  36. 677
  37. 522
  38. 208
  39. 615
  40. 1028

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