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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 784 · 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. 1.467 − 243 =
  2. 2.285 + 443 =
  3. 3.635 + 131 =
  4. 4.302 + 646 =
  5. 5.141 + 315 =
  6. 6.647 − 332 =
  7. 7.130 + 256 =
  8. 8.668 + 371 =
  9. 9.227 + 669 =
  10. 10.415 + 144 =
  11. 11.248 + 405 =
  12. 12.590 + 311 =
  13. 13.250 + 296 =
  14. 14.542 + 318 =
  15. 15.376 + 581 =
  16. 16.652 + 374 =
  17. 17.898 − 646 =
  18. 18.632 − 432 =
  19. 19.680 + 126 =
  20. 20.557 − 252 =
  21. 21.336 + 598 =
  22. 22.416 − 311 =
  23. 23.968 − 826 =
  24. 24.775 − 515 =
  25. 25.395 + 399 =
  26. 26.757 + 381 =
  27. 27.972 − 333 =
  28. 28.191 + 379 =
  29. 29.552 − 297 =
  30. 30.182 + 548 =
  31. 31.446 + 465 =
  32. 32.298 + 127 =
  33. 33.132 + 232 =
  34. 34.535 + 674 =
  35. 35.577 − 318 =
  36. 36.448 − 126 =
  37. 37.554 − 305 =
  38. 38.232 + 518 =
  39. 39.522 + 504 =
  40. 40.516 − 342 =

Answer key

  1. 224
  2. 728
  3. 766
  4. 948
  5. 456
  6. 315
  7. 386
  8. 1039
  9. 896
  10. 559
  11. 653
  12. 901
  13. 546
  14. 860
  15. 957
  16. 1026
  17. 252
  18. 200
  19. 806
  20. 305
  21. 934
  22. 105
  23. 142
  24. 260
  25. 794
  26. 1138
  27. 639
  28. 570
  29. 255
  30. 730
  31. 911
  32. 425
  33. 364
  34. 1209
  35. 259
  36. 322
  37. 249
  38. 750
  39. 1026
  40. 174

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