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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 314 · 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. 1.244 + 305 =
  2. 2.986 − 209 =
  3. 3.919 − 472 =
  4. 4.595 + 327 =
  5. 5.888 − 496 =
  6. 6.458 + 401 =
  7. 7.650 − 192 =
  8. 8.908 − 681 =
  9. 9.456 − 264 =
  10. 10.407 + 227 =
  11. 11.493 − 172 =
  12. 12.930 − 547 =
  13. 13.664 − 202 =
  14. 14.203 + 151 =
  15. 15.746 + 469 =
  16. 16.443 − 138 =
  17. 17.481 + 524 =
  18. 18.236 + 517 =
  19. 19.550 − 251 =
  20. 20.624 − 131 =
  21. 21.520 + 486 =
  22. 22.691 + 668 =
  23. 23.773 − 649 =
  24. 24.474 − 176 =
  25. 25.715 + 247 =
  26. 26.647 + 142 =
  27. 27.370 + 541 =
  28. 28.889 − 246 =
  29. 29.325 + 342 =
  30. 30.720 + 187 =
  31. 31.430 − 289 =
  32. 32.165 + 346 =
  33. 33.430 + 474 =
  34. 34.681 + 196 =
  35. 35.462 + 192 =
  36. 36.178 + 331 =
  37. 37.446 − 341 =
  38. 38.958 − 661 =
  39. 39.582 − 126 =
  40. 40.354 + 391 =

Answer key

  1. 549
  2. 777
  3. 447
  4. 922
  5. 392
  6. 859
  7. 458
  8. 227
  9. 192
  10. 634
  11. 321
  12. 383
  13. 462
  14. 354
  15. 1215
  16. 305
  17. 1005
  18. 753
  19. 299
  20. 493
  21. 1006
  22. 1359
  23. 124
  24. 298
  25. 962
  26. 789
  27. 911
  28. 643
  29. 667
  30. 907
  31. 141
  32. 511
  33. 904
  34. 877
  35. 654
  36. 509
  37. 105
  38. 297
  39. 456
  40. 745

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