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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 992 · 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. 1.306 + 226 =
  2. 2.550 + 661 =
  3. 3.436 + 497 =
  4. 4.311 + 307 =
  5. 5.383 + 436 =
  6. 6.564 + 266 =
  7. 7.461 + 271 =
  8. 8.840 − 591 =
  9. 9.940 − 205 =
  10. 10.677 − 289 =
  11. 11.882 − 347 =
  12. 12.653 + 393 =
  13. 13.612 + 605 =
  14. 14.435 + 346 =
  15. 15.760 + 517 =
  16. 16.609 + 439 =
  17. 17.743 + 471 =
  18. 18.134 + 281 =
  19. 19.212 + 427 =
  20. 20.450 + 182 =
  21. 21.209 + 643 =
  22. 22.452 + 511 =
  23. 23.767 − 187 =
  24. 24.674 − 456 =
  25. 25.968 − 494 =
  26. 26.652 − 265 =
  27. 27.631 + 671 =
  28. 28.582 − 475 =
  29. 29.524 − 181 =
  30. 30.578 − 116 =
  31. 31.666 + 455 =
  32. 32.334 + 386 =
  33. 33.737 − 209 =
  34. 34.212 + 354 =
  35. 35.718 − 505 =
  36. 36.607 − 381 =
  37. 37.418 + 476 =
  38. 38.145 + 272 =
  39. 39.731 + 172 =
  40. 40.469 − 221 =

Answer key

  1. 532
  2. 1211
  3. 933
  4. 618
  5. 819
  6. 830
  7. 732
  8. 249
  9. 735
  10. 388
  11. 535
  12. 1046
  13. 1217
  14. 781
  15. 1277
  16. 1048
  17. 1214
  18. 415
  19. 639
  20. 632
  21. 852
  22. 963
  23. 580
  24. 218
  25. 474
  26. 387
  27. 1302
  28. 107
  29. 343
  30. 462
  31. 1121
  32. 720
  33. 528
  34. 566
  35. 213
  36. 226
  37. 894
  38. 417
  39. 903
  40. 248

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