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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 65 · 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. 1.681 + 471 =
  2. 2.389 + 524 =
  3. 3.455 − 156 =
  4. 4.825 − 154 =
  5. 5.982 − 829 =
  6. 6.458 − 217 =
  7. 7.509 − 185 =
  8. 8.505 + 687 =
  9. 9.470 + 154 =
  10. 10.743 + 213 =
  11. 11.952 − 206 =
  12. 12.162 + 325 =
  13. 13.772 + 492 =
  14. 14.175 + 633 =
  15. 15.443 + 396 =
  16. 16.669 + 449 =
  17. 17.388 + 591 =
  18. 18.415 − 239 =
  19. 19.202 + 411 =
  20. 20.553 + 686 =
  21. 21.669 − 214 =
  22. 22.625 + 418 =
  23. 23.473 + 407 =
  24. 24.130 + 191 =
  25. 25.236 + 235 =
  26. 26.664 − 562 =
  27. 27.500 + 494 =
  28. 28.411 + 289 =
  29. 29.901 − 657 =
  30. 30.611 − 127 =
  31. 31.229 + 293 =
  32. 32.572 − 239 =
  33. 33.398 + 403 =
  34. 34.201 + 211 =
  35. 35.270 + 212 =
  36. 36.471 + 235 =
  37. 37.440 − 149 =
  38. 38.828 − 389 =
  39. 39.719 − 216 =
  40. 40.500 + 184 =

Answer key

  1. 1152
  2. 913
  3. 299
  4. 671
  5. 153
  6. 241
  7. 324
  8. 1192
  9. 624
  10. 956
  11. 746
  12. 487
  13. 1264
  14. 808
  15. 839
  16. 1118
  17. 979
  18. 176
  19. 613
  20. 1239
  21. 455
  22. 1043
  23. 880
  24. 321
  25. 471
  26. 102
  27. 994
  28. 700
  29. 244
  30. 484
  31. 522
  32. 333
  33. 801
  34. 412
  35. 482
  36. 706
  37. 291
  38. 439
  39. 503
  40. 684

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