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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 678 · 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. 1.160 + 641 =
  2. 2.659 + 637 =
  3. 3.653 + 356 =
  4. 4.876 − 692 =
  5. 5.580 − 184 =
  6. 6.603 − 225 =
  7. 7.449 + 242 =
  8. 8.154 + 601 =
  9. 9.261 + 225 =
  10. 10.417 + 181 =
  11. 11.718 − 551 =
  12. 12.822 − 553 =
  13. 13.586 + 122 =
  14. 14.985 − 411 =
  15. 15.464 + 496 =
  16. 16.738 + 638 =
  17. 17.466 + 281 =
  18. 18.809 − 677 =
  19. 19.230 + 578 =
  20. 20.716 + 234 =
  21. 21.131 + 657 =
  22. 22.758 + 339 =
  23. 23.574 + 428 =
  24. 24.881 − 468 =
  25. 25.706 + 398 =
  26. 26.698 + 581 =
  27. 27.565 + 281 =
  28. 28.175 + 267 =
  29. 29.600 − 453 =
  30. 30.357 + 291 =
  31. 31.388 + 587 =
  32. 32.669 − 406 =
  33. 33.136 + 234 =
  34. 34.785 + 285 =
  35. 35.977 − 118 =
  36. 36.591 − 321 =
  37. 37.503 + 641 =
  38. 38.557 + 505 =
  39. 39.558 + 132 =
  40. 40.598 + 396 =

Answer key

  1. 801
  2. 1296
  3. 1009
  4. 184
  5. 396
  6. 378
  7. 691
  8. 755
  9. 486
  10. 598
  11. 167
  12. 269
  13. 708
  14. 574
  15. 960
  16. 1376
  17. 747
  18. 132
  19. 808
  20. 950
  21. 788
  22. 1097
  23. 1002
  24. 413
  25. 1104
  26. 1279
  27. 846
  28. 442
  29. 147
  30. 648
  31. 975
  32. 263
  33. 370
  34. 1070
  35. 859
  36. 270
  37. 1144
  38. 1062
  39. 690
  40. 994

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