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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 618 · 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. 1.549 − 345 =
  2. 2.783 + 473 =
  3. 3.921 − 649 =
  4. 4.779 + 376 =
  5. 5.571 + 129 =
  6. 6.698 + 113 =
  7. 7.243 + 541 =
  8. 8.649 + 172 =
  9. 9.790 − 361 =
  10. 10.573 + 371 =
  11. 11.510 + 443 =
  12. 12.712 − 564 =
  13. 13.446 − 201 =
  14. 14.757 − 535 =
  15. 15.174 + 153 =
  16. 16.273 + 381 =
  17. 17.524 − 302 =
  18. 18.139 + 246 =
  19. 19.725 − 165 =
  20. 20.620 − 344 =
  21. 21.715 + 271 =
  22. 22.694 + 266 =
  23. 23.957 − 811 =
  24. 24.379 + 256 =
  25. 25.201 + 381 =
  26. 26.560 − 434 =
  27. 27.442 + 182 =
  28. 28.639 + 661 =
  29. 29.496 − 151 =
  30. 30.316 + 205 =
  31. 31.987 − 316 =
  32. 32.242 + 369 =
  33. 33.973 − 261 =
  34. 34.285 + 311 =
  35. 35.544 + 523 =
  36. 36.733 + 435 =
  37. 37.521 − 343 =
  38. 38.750 + 377 =
  39. 39.359 + 461 =
  40. 40.185 + 536 =

Answer key

  1. 204
  2. 1256
  3. 272
  4. 1155
  5. 700
  6. 811
  7. 784
  8. 821
  9. 429
  10. 944
  11. 953
  12. 148
  13. 245
  14. 222
  15. 327
  16. 654
  17. 222
  18. 385
  19. 560
  20. 276
  21. 986
  22. 960
  23. 146
  24. 635
  25. 582
  26. 126
  27. 624
  28. 1300
  29. 345
  30. 521
  31. 671
  32. 611
  33. 712
  34. 596
  35. 1067
  36. 1168
  37. 178
  38. 1127
  39. 820
  40. 721

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