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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 91 · 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. 1.935 − 262 =
  2. 2.780 − 124 =
  3. 3.196 + 513 =
  4. 4.623 + 305 =
  5. 5.952 − 389 =
  6. 6.834 − 187 =
  7. 7.591 + 392 =
  8. 8.765 − 376 =
  9. 9.727 + 265 =
  10. 10.659 − 124 =
  11. 11.155 + 591 =
  12. 12.922 − 255 =
  13. 13.640 + 123 =
  14. 14.472 + 311 =
  15. 15.650 + 671 =
  16. 16.780 + 666 =
  17. 17.698 + 184 =
  18. 18.586 + 462 =
  19. 19.238 + 571 =
  20. 20.777 − 329 =
  21. 21.605 − 132 =
  22. 22.468 − 333 =
  23. 23.297 + 252 =
  24. 24.264 + 641 =
  25. 25.182 + 188 =
  26. 26.607 + 338 =
  27. 27.912 − 414 =
  28. 28.201 + 459 =
  29. 29.458 + 393 =
  30. 30.258 + 648 =
  31. 31.672 − 543 =
  32. 32.434 + 116 =
  33. 33.492 − 116 =
  34. 34.720 + 614 =
  35. 35.722 + 337 =
  36. 36.318 + 615 =
  37. 37.807 − 176 =
  38. 38.183 + 601 =
  39. 39.439 + 504 =
  40. 40.273 + 166 =

Answer key

  1. 673
  2. 656
  3. 709
  4. 928
  5. 563
  6. 647
  7. 983
  8. 389
  9. 992
  10. 535
  11. 746
  12. 667
  13. 763
  14. 783
  15. 1321
  16. 1446
  17. 882
  18. 1048
  19. 809
  20. 448
  21. 473
  22. 135
  23. 549
  24. 905
  25. 370
  26. 945
  27. 498
  28. 660
  29. 851
  30. 906
  31. 129
  32. 550
  33. 376
  34. 1334
  35. 1059
  36. 933
  37. 631
  38. 784
  39. 943
  40. 439

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