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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 16 · 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. 1.618 + 232 =
  2. 2.620 − 234 =
  3. 3.459 − 275 =
  4. 4.851 − 529 =
  5. 5.895 − 136 =
  6. 6.305 + 433 =
  7. 7.450 + 394 =
  8. 8.617 + 271 =
  9. 9.814 − 315 =
  10. 10.743 + 452 =
  11. 11.410 + 667 =
  12. 12.867 − 756 =
  13. 13.741 + 241 =
  14. 14.169 + 594 =
  15. 15.350 + 431 =
  16. 16.736 − 251 =
  17. 17.684 − 464 =
  18. 18.779 + 371 =
  19. 19.981 − 562 =
  20. 20.815 − 147 =
  21. 21.766 − 567 =
  22. 22.878 − 637 =
  23. 23.137 + 511 =
  24. 24.453 + 173 =
  25. 25.672 − 531 =
  26. 26.184 + 189 =
  27. 27.764 + 473 =
  28. 28.862 − 562 =
  29. 29.354 + 426 =
  30. 30.672 + 476 =
  31. 31.764 + 127 =
  32. 32.777 − 451 =
  33. 33.961 − 274 =
  34. 34.261 + 263 =
  35. 35.913 − 652 =
  36. 36.235 + 132 =
  37. 37.413 + 191 =
  38. 38.965 − 527 =
  39. 39.355 + 141 =
  40. 40.572 + 337 =

Answer key

  1. 850
  2. 386
  3. 184
  4. 322
  5. 759
  6. 738
  7. 844
  8. 888
  9. 499
  10. 1195
  11. 1077
  12. 111
  13. 982
  14. 763
  15. 781
  16. 485
  17. 220
  18. 1150
  19. 419
  20. 668
  21. 199
  22. 241
  23. 648
  24. 626
  25. 141
  26. 373
  27. 1237
  28. 300
  29. 780
  30. 1148
  31. 891
  32. 326
  33. 687
  34. 524
  35. 261
  36. 367
  37. 604
  38. 438
  39. 496
  40. 909

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