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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 380 · 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. 1.855 − 162 =
  2. 2.730 + 301 =
  3. 3.650 + 649 =
  4. 4.475 + 258 =
  5. 5.451 − 293 =
  6. 6.535 + 511 =
  7. 7.661 + 275 =
  8. 8.735 − 186 =
  9. 9.747 + 253 =
  10. 10.792 − 252 =
  11. 11.460 + 606 =
  12. 12.611 + 582 =
  13. 13.444 + 651 =
  14. 14.255 + 571 =
  15. 15.524 − 219 =
  16. 16.890 − 619 =
  17. 17.968 − 179 =
  18. 18.777 + 321 =
  19. 19.750 + 657 =
  20. 20.611 + 411 =
  21. 21.847 − 727 =
  22. 22.374 + 652 =
  23. 23.320 + 654 =
  24. 24.862 − 294 =
  25. 25.489 − 245 =
  26. 26.781 + 297 =
  27. 27.749 − 156 =
  28. 28.533 − 184 =
  29. 29.631 − 395 =
  30. 30.699 + 289 =
  31. 31.302 + 667 =
  32. 32.669 − 333 =
  33. 33.456 − 232 =
  34. 34.213 + 608 =
  35. 35.695 − 386 =
  36. 36.270 + 293 =
  37. 37.574 − 438 =
  38. 38.468 + 142 =
  39. 39.770 + 684 =
  40. 40.548 − 172 =

Answer key

  1. 693
  2. 1031
  3. 1299
  4. 733
  5. 158
  6. 1046
  7. 936
  8. 549
  9. 1000
  10. 540
  11. 1066
  12. 1193
  13. 1095
  14. 826
  15. 305
  16. 271
  17. 789
  18. 1098
  19. 1407
  20. 1022
  21. 120
  22. 1026
  23. 974
  24. 568
  25. 244
  26. 1078
  27. 593
  28. 349
  29. 236
  30. 988
  31. 969
  32. 336
  33. 224
  34. 821
  35. 309
  36. 563
  37. 136
  38. 610
  39. 1454
  40. 376

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