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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 683 · 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. 1.258 + 351 =
  2. 2.516 − 266 =
  3. 3.965 − 738 =
  4. 4.160 + 397 =
  5. 5.591 + 126 =
  6. 6.303 + 257 =
  7. 7.936 − 489 =
  8. 8.728 + 509 =
  9. 9.579 + 591 =
  10. 10.897 − 182 =
  11. 11.629 − 147 =
  12. 12.748 − 403 =
  13. 13.813 − 664 =
  14. 14.582 − 256 =
  15. 15.518 − 385 =
  16. 16.460 − 356 =
  17. 17.182 + 485 =
  18. 18.162 + 242 =
  19. 19.232 + 665 =
  20. 20.515 + 649 =
  21. 21.575 + 174 =
  22. 22.610 − 341 =
  23. 23.281 + 559 =
  24. 24.465 + 303 =
  25. 25.646 + 126 =
  26. 26.756 − 394 =
  27. 27.449 + 151 =
  28. 28.419 − 114 =
  29. 29.535 + 171 =
  30. 30.300 + 656 =
  31. 31.201 + 444 =
  32. 32.908 − 301 =
  33. 33.306 + 595 =
  34. 34.482 − 356 =
  35. 35.464 + 392 =
  36. 36.510 − 256 =
  37. 37.710 + 429 =
  38. 38.913 − 203 =
  39. 39.736 − 511 =
  40. 40.537 − 372 =

Answer key

  1. 609
  2. 250
  3. 227
  4. 557
  5. 717
  6. 560
  7. 447
  8. 1237
  9. 1170
  10. 715
  11. 482
  12. 345
  13. 149
  14. 326
  15. 133
  16. 104
  17. 667
  18. 404
  19. 897
  20. 1164
  21. 749
  22. 269
  23. 840
  24. 768
  25. 772
  26. 362
  27. 600
  28. 305
  29. 706
  30. 956
  31. 645
  32. 607
  33. 901
  34. 126
  35. 856
  36. 254
  37. 1139
  38. 710
  39. 225
  40. 165

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