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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 798 · 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. 1.594 − 445 =
  2. 2.827 − 486 =
  3. 3.706 + 327 =
  4. 4.639 + 391 =
  5. 5.667 + 603 =
  6. 6.244 + 536 =
  7. 7.528 − 187 =
  8. 8.263 + 189 =
  9. 9.783 − 621 =
  10. 10.641 + 579 =
  11. 11.214 + 161 =
  12. 12.497 + 184 =
  13. 13.264 + 401 =
  14. 14.574 + 451 =
  15. 15.983 − 345 =
  16. 16.190 + 449 =
  17. 17.210 + 481 =
  18. 18.222 + 333 =
  19. 19.206 + 241 =
  20. 20.226 + 353 =
  21. 21.969 − 541 =
  22. 22.659 + 165 =
  23. 23.702 − 137 =
  24. 24.979 − 504 =
  25. 25.545 + 284 =
  26. 26.681 + 415 =
  27. 27.546 − 443 =
  28. 28.248 + 608 =
  29. 29.781 + 278 =
  30. 30.173 + 688 =
  31. 31.471 − 265 =
  32. 32.518 − 375 =
  33. 33.950 − 671 =
  34. 34.640 − 269 =
  35. 35.522 + 172 =
  36. 36.406 + 157 =
  37. 37.496 − 309 =
  38. 38.631 − 431 =
  39. 39.177 + 542 =
  40. 40.508 − 206 =

Answer key

  1. 149
  2. 341
  3. 1033
  4. 1030
  5. 1270
  6. 780
  7. 341
  8. 452
  9. 162
  10. 1220
  11. 375
  12. 681
  13. 665
  14. 1025
  15. 638
  16. 639
  17. 691
  18. 555
  19. 447
  20. 579
  21. 428
  22. 824
  23. 565
  24. 475
  25. 829
  26. 1096
  27. 103
  28. 856
  29. 1059
  30. 861
  31. 206
  32. 143
  33. 279
  34. 371
  35. 694
  36. 563
  37. 187
  38. 200
  39. 719
  40. 302

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