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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 766 · 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. 1.330 + 197 =
  2. 2.527 − 115 =
  3. 3.168 + 391 =
  4. 4.683 − 503 =
  5. 5.590 − 402 =
  6. 6.318 + 351 =
  7. 7.608 − 391 =
  8. 8.632 − 293 =
  9. 9.508 + 278 =
  10. 10.373 + 507 =
  11. 11.674 − 495 =
  12. 12.717 + 527 =
  13. 13.400 + 259 =
  14. 14.268 + 363 =
  15. 15.972 − 752 =
  16. 16.405 + 165 =
  17. 17.483 − 376 =
  18. 18.461 − 171 =
  19. 19.132 + 362 =
  20. 20.545 + 226 =
  21. 21.516 − 135 =
  22. 22.540 + 343 =
  23. 23.873 − 158 =
  24. 24.960 − 431 =
  25. 25.660 + 201 =
  26. 26.623 + 277 =
  27. 27.638 − 247 =
  28. 28.159 + 621 =
  29. 29.544 − 412 =
  30. 30.410 + 631 =
  31. 31.457 − 244 =
  32. 32.779 − 374 =
  33. 33.139 + 624 =
  34. 34.736 + 229 =
  35. 35.625 − 524 =
  36. 36.610 + 445 =
  37. 37.768 + 407 =
  38. 38.487 − 143 =
  39. 39.467 − 187 =
  40. 40.412 + 113 =

Answer key

  1. 527
  2. 412
  3. 559
  4. 180
  5. 188
  6. 669
  7. 217
  8. 339
  9. 786
  10. 880
  11. 179
  12. 1244
  13. 659
  14. 631
  15. 220
  16. 570
  17. 107
  18. 290
  19. 494
  20. 771
  21. 381
  22. 883
  23. 715
  24. 529
  25. 861
  26. 900
  27. 391
  28. 780
  29. 132
  30. 1041
  31. 213
  32. 405
  33. 763
  34. 965
  35. 101
  36. 1055
  37. 1175
  38. 344
  39. 280
  40. 525

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