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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 869 · 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. 1.418 − 165 =
  2. 2.529 + 434 =
  3. 3.564 + 207 =
  4. 4.561 + 135 =
  5. 5.805 − 528 =
  6. 6.377 + 458 =
  7. 7.496 − 221 =
  8. 8.692 − 571 =
  9. 9.610 − 448 =
  10. 10.874 − 481 =
  11. 11.932 − 199 =
  12. 12.958 − 166 =
  13. 13.571 − 242 =
  14. 14.618 + 591 =
  15. 15.956 − 641 =
  16. 16.769 − 219 =
  17. 17.688 − 213 =
  18. 18.568 + 177 =
  19. 19.200 + 511 =
  20. 20.166 + 187 =
  21. 21.232 + 541 =
  22. 22.235 + 631 =
  23. 23.824 − 343 =
  24. 24.286 + 496 =
  25. 25.416 + 621 =
  26. 26.787 + 577 =
  27. 27.425 − 211 =
  28. 28.746 + 276 =
  29. 29.750 − 523 =
  30. 30.390 + 423 =
  31. 31.622 − 294 =
  32. 32.618 − 308 =
  33. 33.916 − 812 =
  34. 34.390 + 353 =
  35. 35.705 + 643 =
  36. 36.428 + 163 =
  37. 37.911 − 319 =
  38. 38.704 − 252 =
  39. 39.181 + 526 =
  40. 40.628 + 358 =

Answer key

  1. 253
  2. 963
  3. 771
  4. 696
  5. 277
  6. 835
  7. 275
  8. 121
  9. 162
  10. 393
  11. 733
  12. 792
  13. 329
  14. 1209
  15. 315
  16. 550
  17. 475
  18. 745
  19. 711
  20. 353
  21. 773
  22. 866
  23. 481
  24. 782
  25. 1037
  26. 1364
  27. 214
  28. 1022
  29. 227
  30. 813
  31. 328
  32. 310
  33. 104
  34. 743
  35. 1348
  36. 591
  37. 592
  38. 452
  39. 707
  40. 986

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