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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 278 · 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. 1.600 + 428 =
  2. 2.710 − 522 =
  3. 3.730 − 227 =
  4. 4.332 + 223 =
  5. 5.128 + 248 =
  6. 6.620 + 362 =
  7. 7.740 + 403 =
  8. 8.497 − 361 =
  9. 9.317 + 166 =
  10. 10.343 + 633 =
  11. 11.534 − 195 =
  12. 12.458 − 306 =
  13. 13.426 + 131 =
  14. 14.369 + 447 =
  15. 15.249 + 502 =
  16. 16.973 − 773 =
  17. 17.743 − 388 =
  18. 18.729 + 655 =
  19. 19.484 − 119 =
  20. 20.579 − 206 =
  21. 21.717 − 264 =
  22. 22.810 − 484 =
  23. 23.692 + 517 =
  24. 24.522 + 651 =
  25. 25.164 + 557 =
  26. 26.557 − 134 =
  27. 27.855 − 632 =
  28. 28.626 − 452 =
  29. 29.968 − 121 =
  30. 30.420 − 157 =
  31. 31.791 − 125 =
  32. 32.888 − 174 =
  33. 33.353 + 123 =
  34. 34.482 + 251 =
  35. 35.193 + 496 =
  36. 36.769 + 484 =
  37. 37.502 + 635 =
  38. 38.767 + 244 =
  39. 39.453 + 431 =
  40. 40.774 − 596 =

Answer key

  1. 1028
  2. 188
  3. 503
  4. 555
  5. 376
  6. 982
  7. 1143
  8. 136
  9. 483
  10. 976
  11. 339
  12. 152
  13. 557
  14. 816
  15. 751
  16. 200
  17. 355
  18. 1384
  19. 365
  20. 373
  21. 453
  22. 326
  23. 1209
  24. 1173
  25. 721
  26. 423
  27. 223
  28. 174
  29. 847
  30. 263
  31. 666
  32. 714
  33. 476
  34. 733
  35. 689
  36. 1253
  37. 1137
  38. 1011
  39. 884
  40. 178

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