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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 759 · 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. 1.188 + 566 =
  2. 2.259 + 601 =
  3. 3.640 + 294 =
  4. 4.661 + 207 =
  5. 5.523 + 181 =
  6. 6.531 − 129 =
  7. 7.669 − 359 =
  8. 8.947 − 281 =
  9. 9.589 + 327 =
  10. 10.767 − 582 =
  11. 11.364 + 543 =
  12. 12.930 − 319 =
  13. 13.619 − 248 =
  14. 14.330 + 117 =
  15. 15.935 − 303 =
  16. 16.727 − 459 =
  17. 17.213 + 605 =
  18. 18.604 − 371 =
  19. 19.676 + 472 =
  20. 20.776 + 152 =
  21. 21.647 + 564 =
  22. 22.315 + 525 =
  23. 23.834 − 501 =
  24. 24.437 + 448 =
  25. 25.627 − 138 =
  26. 26.645 + 379 =
  27. 27.880 − 501 =
  28. 28.726 + 206 =
  29. 29.641 − 482 =
  30. 30.448 − 162 =
  31. 31.771 − 507 =
  32. 32.274 + 611 =
  33. 33.387 + 394 =
  34. 34.287 + 191 =
  35. 35.621 + 598 =
  36. 36.895 − 191 =
  37. 37.536 − 168 =
  38. 38.786 + 122 =
  39. 39.616 − 305 =
  40. 40.823 − 169 =

Answer key

  1. 754
  2. 860
  3. 934
  4. 868
  5. 704
  6. 402
  7. 310
  8. 666
  9. 916
  10. 185
  11. 907
  12. 611
  13. 371
  14. 447
  15. 632
  16. 268
  17. 818
  18. 233
  19. 1148
  20. 928
  21. 1211
  22. 840
  23. 333
  24. 885
  25. 489
  26. 1024
  27. 379
  28. 932
  29. 159
  30. 286
  31. 264
  32. 885
  33. 781
  34. 478
  35. 1219
  36. 704
  37. 368
  38. 908
  39. 311
  40. 654

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