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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 832 · 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. 1.678 + 664 =
  2. 2.732 + 221 =
  3. 3.880 − 481 =
  4. 4.718 + 151 =
  5. 5.936 − 665 =
  6. 6.979 − 295 =
  7. 7.289 + 586 =
  8. 8.867 − 266 =
  9. 9.834 − 651 =
  10. 10.791 − 651 =
  11. 11.336 + 507 =
  12. 12.777 + 395 =
  13. 13.510 − 353 =
  14. 14.787 − 156 =
  15. 15.736 − 551 =
  16. 16.253 + 617 =
  17. 17.787 + 272 =
  18. 18.720 + 175 =
  19. 19.690 − 278 =
  20. 20.362 + 659 =
  21. 21.464 − 132 =
  22. 22.508 − 189 =
  23. 23.421 + 248 =
  24. 24.463 + 663 =
  25. 25.649 + 216 =
  26. 26.143 + 654 =
  27. 27.205 + 305 =
  28. 28.883 − 652 =
  29. 29.274 + 349 =
  30. 30.670 + 621 =
  31. 31.977 − 202 =
  32. 32.726 − 161 =
  33. 33.486 + 154 =
  34. 34.514 − 144 =
  35. 35.458 + 423 =
  36. 36.766 − 127 =
  37. 37.944 − 715 =
  38. 38.475 − 343 =
  39. 39.597 + 458 =
  40. 40.712 − 131 =

Answer key

  1. 1342
  2. 953
  3. 399
  4. 869
  5. 271
  6. 684
  7. 875
  8. 601
  9. 183
  10. 140
  11. 843
  12. 1172
  13. 157
  14. 631
  15. 185
  16. 870
  17. 1059
  18. 895
  19. 412
  20. 1021
  21. 332
  22. 319
  23. 669
  24. 1126
  25. 865
  26. 797
  27. 510
  28. 231
  29. 623
  30. 1291
  31. 775
  32. 565
  33. 640
  34. 370
  35. 881
  36. 639
  37. 229
  38. 132
  39. 1055
  40. 581

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