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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 310 · 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. 1.437 − 163 =
  2. 2.273 + 647 =
  3. 3.829 − 187 =
  4. 4.947 − 514 =
  5. 5.466 + 264 =
  6. 6.586 − 141 =
  7. 7.475 − 206 =
  8. 8.489 − 357 =
  9. 9.216 + 247 =
  10. 10.520 − 189 =
  11. 11.291 + 638 =
  12. 12.892 − 777 =
  13. 13.874 − 444 =
  14. 14.649 + 386 =
  15. 15.491 + 325 =
  16. 16.443 − 173 =
  17. 17.360 + 325 =
  18. 18.703 + 195 =
  19. 19.955 − 189 =
  20. 20.625 − 152 =
  21. 21.321 + 425 =
  22. 22.610 + 663 =
  23. 23.583 − 177 =
  24. 24.641 − 337 =
  25. 25.757 + 461 =
  26. 26.576 − 284 =
  27. 27.744 + 268 =
  28. 28.563 + 176 =
  29. 29.846 − 549 =
  30. 30.689 + 589 =
  31. 31.447 + 207 =
  32. 32.638 + 663 =
  33. 33.512 − 368 =
  34. 34.532 + 157 =
  35. 35.624 + 615 =
  36. 36.502 − 202 =
  37. 37.617 + 642 =
  38. 38.417 + 638 =
  39. 39.312 + 258 =
  40. 40.240 + 542 =

Answer key

  1. 274
  2. 920
  3. 642
  4. 433
  5. 730
  6. 445
  7. 269
  8. 132
  9. 463
  10. 331
  11. 929
  12. 115
  13. 430
  14. 1035
  15. 816
  16. 270
  17. 685
  18. 898
  19. 766
  20. 473
  21. 746
  22. 1273
  23. 406
  24. 304
  25. 1218
  26. 292
  27. 1012
  28. 739
  29. 297
  30. 1278
  31. 654
  32. 1301
  33. 144
  34. 689
  35. 1239
  36. 300
  37. 1259
  38. 1055
  39. 570
  40. 782

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