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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 52 · 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. 1.571 + 491 =
  2. 2.589 + 556 =
  3. 3.358 + 282 =
  4. 4.706 − 141 =
  5. 5.772 + 664 =
  6. 6.156 + 124 =
  7. 7.300 + 361 =
  8. 8.637 − 367 =
  9. 9.469 − 353 =
  10. 10.439 − 176 =
  11. 11.544 − 291 =
  12. 12.678 + 167 =
  13. 13.823 − 175 =
  14. 14.478 − 267 =
  15. 15.317 + 357 =
  16. 16.630 − 279 =
  17. 17.194 + 522 =
  18. 18.869 − 154 =
  19. 19.554 − 251 =
  20. 20.415 + 176 =
  21. 21.207 + 176 =
  22. 22.269 + 253 =
  23. 23.595 + 389 =
  24. 24.346 + 405 =
  25. 25.746 + 491 =
  26. 26.815 − 511 =
  27. 27.694 − 324 =
  28. 28.151 + 127 =
  29. 29.933 − 497 =
  30. 30.584 − 455 =
  31. 31.434 + 611 =
  32. 32.246 + 367 =
  33. 33.721 + 664 =
  34. 34.677 + 681 =
  35. 35.426 + 316 =
  36. 36.277 + 548 =
  37. 37.638 − 161 =
  38. 38.565 − 272 =
  39. 39.138 + 234 =
  40. 40.827 − 123 =

Answer key

  1. 1062
  2. 1145
  3. 640
  4. 565
  5. 1436
  6. 280
  7. 661
  8. 270
  9. 116
  10. 263
  11. 253
  12. 845
  13. 648
  14. 211
  15. 674
  16. 351
  17. 716
  18. 715
  19. 303
  20. 591
  21. 383
  22. 522
  23. 984
  24. 751
  25. 1237
  26. 304
  27. 370
  28. 278
  29. 436
  30. 129
  31. 1045
  32. 613
  33. 1385
  34. 1358
  35. 742
  36. 825
  37. 477
  38. 293
  39. 372
  40. 704

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