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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 75 · 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. 1.502 − 314 =
  2. 2.317 + 134 =
  3. 3.730 − 394 =
  4. 4.399 + 247 =
  5. 5.771 + 489 =
  6. 6.346 + 176 =
  7. 7.433 − 132 =
  8. 8.941 − 161 =
  9. 9.586 − 173 =
  10. 10.174 + 598 =
  11. 11.769 + 303 =
  12. 12.264 + 471 =
  13. 13.744 − 553 =
  14. 14.718 − 217 =
  15. 15.669 − 246 =
  16. 16.810 − 596 =
  17. 17.342 + 501 =
  18. 18.397 + 156 =
  19. 19.669 + 573 =
  20. 20.948 − 424 =
  21. 21.562 + 115 =
  22. 22.533 − 421 =
  23. 23.572 + 441 =
  24. 24.781 − 264 =
  25. 25.427 − 321 =
  26. 26.648 − 181 =
  27. 27.419 + 422 =
  28. 28.136 + 454 =
  29. 29.244 + 175 =
  30. 30.506 − 116 =
  31. 31.208 + 454 =
  32. 32.443 + 669 =
  33. 33.131 + 232 =
  34. 34.464 + 367 =
  35. 35.148 + 206 =
  36. 36.247 + 685 =
  37. 37.435 + 221 =
  38. 38.540 + 384 =
  39. 39.726 − 196 =
  40. 40.279 + 481 =

Answer key

  1. 188
  2. 451
  3. 336
  4. 646
  5. 1260
  6. 522
  7. 301
  8. 780
  9. 413
  10. 772
  11. 1072
  12. 735
  13. 191
  14. 501
  15. 423
  16. 214
  17. 843
  18. 553
  19. 1242
  20. 524
  21. 677
  22. 112
  23. 1013
  24. 517
  25. 106
  26. 467
  27. 841
  28. 590
  29. 419
  30. 390
  31. 662
  32. 1112
  33. 363
  34. 831
  35. 354
  36. 932
  37. 656
  38. 924
  39. 530
  40. 760

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