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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 938 · 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. 1.340 + 186 =
  2. 2.795 − 141 =
  3. 3.456 + 434 =
  4. 4.644 + 274 =
  5. 5.149 + 628 =
  6. 6.501 + 279 =
  7. 7.576 + 149 =
  8. 8.511 + 151 =
  9. 9.747 − 467 =
  10. 10.164 + 534 =
  11. 11.772 − 441 =
  12. 12.471 + 133 =
  13. 13.494 + 158 =
  14. 14.610 + 183 =
  15. 15.229 + 657 =
  16. 16.346 + 465 =
  17. 17.457 − 236 =
  18. 18.965 − 345 =
  19. 19.274 + 344 =
  20. 20.429 − 311 =
  21. 21.725 − 605 =
  22. 22.775 − 508 =
  23. 23.416 + 352 =
  24. 24.157 + 381 =
  25. 25.622 + 166 =
  26. 26.600 − 381 =
  27. 27.634 + 183 =
  28. 28.585 − 358 =
  29. 29.447 − 209 =
  30. 30.197 + 666 =
  31. 31.463 − 204 =
  32. 32.807 − 613 =
  33. 33.633 − 529 =
  34. 34.730 + 175 =
  35. 35.419 + 427 =
  36. 36.744 − 557 =
  37. 37.875 − 195 =
  38. 38.573 − 271 =
  39. 39.603 − 461 =
  40. 40.750 − 182 =

Answer key

  1. 526
  2. 654
  3. 890
  4. 918
  5. 777
  6. 780
  7. 725
  8. 662
  9. 280
  10. 698
  11. 331
  12. 604
  13. 652
  14. 793
  15. 886
  16. 811
  17. 221
  18. 620
  19. 618
  20. 118
  21. 120
  22. 267
  23. 768
  24. 538
  25. 788
  26. 219
  27. 817
  28. 227
  29. 238
  30. 863
  31. 259
  32. 194
  33. 104
  34. 905
  35. 846
  36. 187
  37. 680
  38. 302
  39. 142
  40. 568

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