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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 922 · 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. 1.432 − 281 =
  2. 2.613 − 123 =
  3. 3.984 − 654 =
  4. 4.460 − 299 =
  5. 5.363 + 612 =
  6. 6.451 + 224 =
  7. 7.314 + 681 =
  8. 8.763 − 266 =
  9. 9.447 − 181 =
  10. 10.481 − 336 =
  11. 11.612 + 641 =
  12. 12.481 − 179 =
  13. 13.673 − 158 =
  14. 14.763 − 186 =
  15. 15.965 − 731 =
  16. 16.744 − 304 =
  17. 17.772 − 246 =
  18. 18.469 + 267 =
  19. 19.258 + 567 =
  20. 20.380 + 561 =
  21. 21.423 − 281 =
  22. 22.436 − 217 =
  23. 23.514 + 366 =
  24. 24.829 − 211 =
  25. 25.466 − 278 =
  26. 26.513 − 123 =
  27. 27.785 + 167 =
  28. 28.462 − 328 =
  29. 29.486 − 188 =
  30. 30.465 − 157 =
  31. 31.466 + 488 =
  32. 32.408 + 604 =
  33. 33.176 + 264 =
  34. 34.482 + 665 =
  35. 35.645 − 123 =
  36. 36.810 − 668 =
  37. 37.513 − 344 =
  38. 38.693 + 308 =
  39. 39.718 − 335 =
  40. 40.547 + 599 =

Answer key

  1. 151
  2. 490
  3. 330
  4. 161
  5. 975
  6. 675
  7. 995
  8. 497
  9. 266
  10. 145
  11. 1253
  12. 302
  13. 515
  14. 577
  15. 234
  16. 440
  17. 526
  18. 736
  19. 825
  20. 941
  21. 142
  22. 219
  23. 880
  24. 618
  25. 188
  26. 390
  27. 952
  28. 134
  29. 298
  30. 308
  31. 954
  32. 1012
  33. 440
  34. 1147
  35. 522
  36. 142
  37. 169
  38. 1001
  39. 383
  40. 1146

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