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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 267 · 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. 1.836 − 523 =
  2. 2.234 + 417 =
  3. 3.467 − 331 =
  4. 4.438 − 133 =
  5. 5.176 + 236 =
  6. 6.683 + 244 =
  7. 7.921 − 526 =
  8. 8.287 + 625 =
  9. 9.681 − 381 =
  10. 10.754 + 124 =
  11. 11.770 − 357 =
  12. 12.329 + 131 =
  13. 13.393 + 206 =
  14. 14.679 − 164 =
  15. 15.234 + 261 =
  16. 16.531 − 388 =
  17. 17.130 + 386 =
  18. 18.897 − 611 =
  19. 19.735 + 442 =
  20. 20.729 + 321 =
  21. 21.651 − 532 =
  22. 22.531 + 661 =
  23. 23.804 − 423 =
  24. 24.417 − 161 =
  25. 25.779 + 624 =
  26. 26.710 − 445 =
  27. 27.540 − 179 =
  28. 28.512 − 342 =
  29. 29.692 + 247 =
  30. 30.757 − 575 =
  31. 31.416 + 214 =
  32. 32.768 − 241 =
  33. 33.893 − 642 =
  34. 34.564 − 177 =
  35. 35.780 + 172 =
  36. 36.682 − 399 =
  37. 37.688 + 285 =
  38. 38.582 + 658 =
  39. 39.528 − 236 =
  40. 40.428 − 152 =

Answer key

  1. 313
  2. 651
  3. 136
  4. 305
  5. 412
  6. 927
  7. 395
  8. 912
  9. 300
  10. 878
  11. 413
  12. 460
  13. 599
  14. 515
  15. 495
  16. 143
  17. 516
  18. 286
  19. 1177
  20. 1050
  21. 119
  22. 1192
  23. 381
  24. 256
  25. 1403
  26. 265
  27. 361
  28. 170
  29. 939
  30. 182
  31. 630
  32. 527
  33. 251
  34. 387
  35. 952
  36. 283
  37. 973
  38. 1240
  39. 292
  40. 276

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