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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 518 · 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. 1.161 + 154 =
  2. 2.564 + 432 =
  3. 3.508 − 157 =
  4. 4.309 + 252 =
  5. 5.405 + 515 =
  6. 6.942 − 159 =
  7. 7.543 − 183 =
  8. 8.842 − 721 =
  9. 9.760 + 471 =
  10. 10.451 − 211 =
  11. 11.302 + 138 =
  12. 12.251 + 204 =
  13. 13.218 + 315 =
  14. 14.405 + 251 =
  15. 15.572 + 269 =
  16. 16.668 + 402 =
  17. 17.319 + 271 =
  18. 18.788 + 516 =
  19. 19.591 + 392 =
  20. 20.287 + 141 =
  21. 21.533 − 281 =
  22. 22.532 + 608 =
  23. 23.733 + 511 =
  24. 24.971 − 273 =
  25. 25.784 + 311 =
  26. 26.235 + 481 =
  27. 27.484 − 206 =
  28. 28.278 + 355 =
  29. 29.510 − 297 =
  30. 30.412 − 196 =
  31. 31.611 + 686 =
  32. 32.896 − 613 =
  33. 33.719 + 121 =
  34. 34.790 − 487 =
  35. 35.126 + 501 =
  36. 36.627 − 436 =
  37. 37.810 − 585 =
  38. 38.825 − 411 =
  39. 39.855 − 632 =
  40. 40.257 + 166 =

Answer key

  1. 315
  2. 996
  3. 351
  4. 561
  5. 920
  6. 783
  7. 360
  8. 121
  9. 1231
  10. 240
  11. 440
  12. 455
  13. 533
  14. 656
  15. 841
  16. 1070
  17. 590
  18. 1304
  19. 983
  20. 428
  21. 252
  22. 1140
  23. 1244
  24. 698
  25. 1095
  26. 716
  27. 278
  28. 633
  29. 213
  30. 216
  31. 1297
  32. 283
  33. 840
  34. 303
  35. 627
  36. 191
  37. 225
  38. 414
  39. 223
  40. 423

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