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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 265 · 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. 1.959 − 213 =
  2. 2.766 − 589 =
  3. 3.397 + 436 =
  4. 4.347 + 286 =
  5. 5.377 + 633 =
  6. 6.439 + 431 =
  7. 7.683 − 536 =
  8. 8.541 + 132 =
  9. 9.595 − 452 =
  10. 10.483 + 536 =
  11. 11.730 + 142 =
  12. 12.605 + 489 =
  13. 13.145 + 265 =
  14. 14.617 − 376 =
  15. 15.731 − 554 =
  16. 16.170 + 465 =
  17. 17.839 − 598 =
  18. 18.127 + 543 =
  19. 19.482 − 235 =
  20. 20.281 + 201 =
  21. 21.159 + 234 =
  22. 22.515 − 244 =
  23. 23.514 + 513 =
  24. 24.703 + 311 =
  25. 25.672 + 446 =
  26. 26.405 + 178 =
  27. 27.465 − 156 =
  28. 28.527 − 191 =
  29. 29.553 − 386 =
  30. 30.751 − 534 =
  31. 31.444 − 336 =
  32. 32.929 − 664 =
  33. 33.828 − 149 =
  34. 34.346 + 595 =
  35. 35.398 + 573 =
  36. 36.315 + 589 =
  37. 37.397 + 153 =
  38. 38.422 + 226 =
  39. 39.494 − 381 =
  40. 40.903 − 486 =

Answer key

  1. 746
  2. 177
  3. 833
  4. 633
  5. 1010
  6. 870
  7. 147
  8. 673
  9. 143
  10. 1019
  11. 872
  12. 1094
  13. 410
  14. 241
  15. 177
  16. 635
  17. 241
  18. 670
  19. 247
  20. 482
  21. 393
  22. 271
  23. 1027
  24. 1014
  25. 1118
  26. 583
  27. 309
  28. 336
  29. 167
  30. 217
  31. 108
  32. 265
  33. 679
  34. 941
  35. 971
  36. 904
  37. 550
  38. 648
  39. 113
  40. 417

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