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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 441 · 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. 1.732 + 401 =
  2. 2.750 − 394 =
  3. 3.476 − 153 =
  4. 4.913 − 122 =
  5. 5.413 − 159 =
  6. 6.576 + 604 =
  7. 7.173 + 221 =
  8. 8.917 − 605 =
  9. 9.282 + 687 =
  10. 10.517 − 171 =
  11. 11.384 + 268 =
  12. 12.449 − 294 =
  13. 13.765 + 448 =
  14. 14.146 + 643 =
  15. 15.916 − 591 =
  16. 16.639 − 284 =
  17. 17.321 + 299 =
  18. 18.861 − 148 =
  19. 19.759 − 521 =
  20. 20.806 − 146 =
  21. 21.847 − 193 =
  22. 22.425 + 415 =
  23. 23.287 + 666 =
  24. 24.300 + 224 =
  25. 25.818 − 673 =
  26. 26.199 + 537 =
  27. 27.858 − 566 =
  28. 28.213 + 402 =
  29. 29.668 − 444 =
  30. 30.788 + 222 =
  31. 31.739 + 645 =
  32. 32.976 − 753 =
  33. 33.302 + 283 =
  34. 34.661 − 199 =
  35. 35.224 + 659 =
  36. 36.977 − 258 =
  37. 37.659 − 346 =
  38. 38.163 + 626 =
  39. 39.430 − 121 =
  40. 40.502 + 285 =

Answer key

  1. 1133
  2. 356
  3. 323
  4. 791
  5. 254
  6. 1180
  7. 394
  8. 312
  9. 969
  10. 346
  11. 652
  12. 155
  13. 1213
  14. 789
  15. 325
  16. 355
  17. 620
  18. 713
  19. 238
  20. 660
  21. 654
  22. 840
  23. 953
  24. 524
  25. 145
  26. 736
  27. 292
  28. 615
  29. 224
  30. 1010
  31. 1384
  32. 223
  33. 585
  34. 462
  35. 883
  36. 719
  37. 313
  38. 789
  39. 309
  40. 787

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