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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 793 · 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. 1.427 − 168 =
  2. 2.123 + 411 =
  3. 3.287 + 306 =
  4. 4.930 − 301 =
  5. 5.339 + 226 =
  6. 6.201 + 167 =
  7. 7.206 + 288 =
  8. 8.596 − 224 =
  9. 9.744 + 393 =
  10. 10.512 − 399 =
  11. 11.686 − 561 =
  12. 12.546 − 303 =
  13. 13.547 + 531 =
  14. 14.511 − 152 =
  15. 15.810 − 232 =
  16. 16.711 − 228 =
  17. 17.478 − 176 =
  18. 18.244 + 413 =
  19. 19.187 + 494 =
  20. 20.544 + 675 =
  21. 21.582 − 211 =
  22. 22.715 − 154 =
  23. 23.581 + 597 =
  24. 24.124 + 205 =
  25. 25.732 − 498 =
  26. 26.488 − 155 =
  27. 27.535 − 389 =
  28. 28.529 + 241 =
  29. 29.336 + 521 =
  30. 30.833 − 344 =
  31. 31.252 + 651 =
  32. 32.373 + 271 =
  33. 33.442 − 158 =
  34. 34.674 − 231 =
  35. 35.932 − 254 =
  36. 36.130 + 434 =
  37. 37.712 + 266 =
  38. 38.198 + 245 =
  39. 39.623 − 287 =
  40. 40.525 − 146 =

Answer key

  1. 259
  2. 534
  3. 593
  4. 629
  5. 565
  6. 368
  7. 494
  8. 372
  9. 1137
  10. 113
  11. 125
  12. 243
  13. 1078
  14. 359
  15. 578
  16. 483
  17. 302
  18. 657
  19. 681
  20. 1219
  21. 371
  22. 561
  23. 1178
  24. 329
  25. 234
  26. 333
  27. 146
  28. 770
  29. 857
  30. 489
  31. 903
  32. 644
  33. 284
  34. 443
  35. 678
  36. 564
  37. 978
  38. 443
  39. 336
  40. 379

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