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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 490 · 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. 1.530 − 229 =
  2. 2.429 − 303 =
  3. 3.587 − 474 =
  4. 4.624 − 166 =
  5. 5.371 + 163 =
  6. 6.273 + 125 =
  7. 7.241 + 496 =
  8. 8.196 + 193 =
  9. 9.568 − 224 =
  10. 10.319 + 399 =
  11. 11.803 − 221 =
  12. 12.571 − 155 =
  13. 13.497 − 291 =
  14. 14.530 + 511 =
  15. 15.789 + 495 =
  16. 16.226 + 675 =
  17. 17.648 + 301 =
  18. 18.483 + 318 =
  19. 19.584 + 541 =
  20. 20.414 − 226 =
  21. 21.420 − 301 =
  22. 22.574 − 193 =
  23. 23.603 + 492 =
  24. 24.159 + 591 =
  25. 25.592 − 258 =
  26. 26.776 + 258 =
  27. 27.255 + 241 =
  28. 28.675 + 171 =
  29. 29.325 + 349 =
  30. 30.135 + 586 =
  31. 31.306 + 507 =
  32. 32.676 + 666 =
  33. 33.779 + 417 =
  34. 34.689 − 228 =
  35. 35.733 − 362 =
  36. 36.599 + 364 =
  37. 37.527 − 169 =
  38. 38.546 − 401 =
  39. 39.430 + 508 =
  40. 40.524 + 663 =

Answer key

  1. 301
  2. 126
  3. 113
  4. 458
  5. 534
  6. 398
  7. 737
  8. 389
  9. 344
  10. 718
  11. 582
  12. 416
  13. 206
  14. 1041
  15. 1284
  16. 901
  17. 949
  18. 801
  19. 1125
  20. 188
  21. 119
  22. 381
  23. 1095
  24. 750
  25. 334
  26. 1034
  27. 496
  28. 846
  29. 674
  30. 721
  31. 813
  32. 1342
  33. 1196
  34. 461
  35. 371
  36. 963
  37. 358
  38. 145
  39. 938
  40. 1187

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