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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 402 · 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. 1.188 + 467 =
  2. 2.447 − 181 =
  3. 3.533 + 572 =
  4. 4.514 + 269 =
  5. 5.647 − 259 =
  6. 6.512 − 284 =
  7. 7.568 + 568 =
  8. 8.366 + 183 =
  9. 9.134 + 164 =
  10. 10.362 + 371 =
  11. 11.763 − 131 =
  12. 12.773 − 174 =
  13. 13.174 + 445 =
  14. 14.170 + 232 =
  15. 15.508 + 421 =
  16. 16.587 − 244 =
  17. 17.288 + 655 =
  18. 18.529 + 283 =
  19. 19.331 + 657 =
  20. 20.285 + 659 =
  21. 21.683 − 461 =
  22. 22.696 + 137 =
  23. 23.747 − 151 =
  24. 24.789 − 481 =
  25. 25.516 − 189 =
  26. 26.658 − 199 =
  27. 27.514 + 173 =
  28. 28.424 + 434 =
  29. 29.578 + 496 =
  30. 30.294 + 313 =
  31. 31.241 + 601 =
  32. 32.712 − 513 =
  33. 33.908 − 556 =
  34. 34.963 − 847 =
  35. 35.377 + 561 =
  36. 36.272 + 415 =
  37. 37.618 − 403 =
  38. 38.424 + 149 =
  39. 39.180 + 452 =
  40. 40.310 + 226 =

Answer key

  1. 655
  2. 266
  3. 1105
  4. 783
  5. 388
  6. 228
  7. 1136
  8. 549
  9. 298
  10. 733
  11. 632
  12. 599
  13. 619
  14. 402
  15. 929
  16. 343
  17. 943
  18. 812
  19. 988
  20. 944
  21. 222
  22. 833
  23. 596
  24. 308
  25. 327
  26. 459
  27. 687
  28. 858
  29. 1074
  30. 607
  31. 842
  32. 199
  33. 352
  34. 116
  35. 938
  36. 687
  37. 215
  38. 573
  39. 632
  40. 536

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