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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 694 · 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. 1.723 + 535 =
  2. 2.750 + 492 =
  3. 3.576 + 123 =
  4. 4.269 + 217 =
  5. 5.202 + 274 =
  6. 6.419 − 308 =
  7. 7.698 + 307 =
  8. 8.328 + 639 =
  9. 9.884 − 561 =
  10. 10.194 + 231 =
  11. 11.317 + 579 =
  12. 12.200 + 512 =
  13. 13.945 − 835 =
  14. 14.763 + 195 =
  15. 15.934 − 743 =
  16. 16.674 − 326 =
  17. 17.480 − 306 =
  18. 18.358 + 202 =
  19. 19.887 − 341 =
  20. 20.555 + 529 =
  21. 21.395 + 633 =
  22. 22.768 + 373 =
  23. 23.518 − 369 =
  24. 24.865 − 565 =
  25. 25.608 + 264 =
  26. 26.975 − 371 =
  27. 27.191 + 422 =
  28. 28.283 + 666 =
  29. 29.202 + 486 =
  30. 30.703 + 543 =
  31. 31.923 − 529 =
  32. 32.669 + 444 =
  33. 33.724 − 217 =
  34. 34.525 − 234 =
  35. 35.684 + 688 =
  36. 36.559 − 429 =
  37. 37.171 + 287 =
  38. 38.791 − 251 =
  39. 39.654 − 437 =
  40. 40.302 + 396 =

Answer key

  1. 1258
  2. 1242
  3. 699
  4. 486
  5. 476
  6. 111
  7. 1005
  8. 967
  9. 323
  10. 425
  11. 896
  12. 712
  13. 110
  14. 958
  15. 191
  16. 348
  17. 174
  18. 560
  19. 546
  20. 1084
  21. 1028
  22. 1141
  23. 149
  24. 300
  25. 872
  26. 604
  27. 613
  28. 949
  29. 688
  30. 1246
  31. 394
  32. 1113
  33. 507
  34. 291
  35. 1372
  36. 130
  37. 458
  38. 540
  39. 217
  40. 698

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