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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 293 · 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. 1.219 + 151 =
  2. 2.221 + 264 =
  3. 3.979 − 265 =
  4. 4.880 − 147 =
  5. 5.223 + 341 =
  6. 6.954 − 278 =
  7. 7.297 + 521 =
  8. 8.477 − 336 =
  9. 9.318 + 243 =
  10. 10.300 + 557 =
  11. 11.296 + 281 =
  12. 12.509 + 248 =
  13. 13.819 − 113 =
  14. 14.817 − 272 =
  15. 15.629 + 193 =
  16. 16.607 − 299 =
  17. 17.505 + 227 =
  18. 18.693 − 161 =
  19. 19.470 − 346 =
  20. 20.578 + 265 =
  21. 21.350 + 461 =
  22. 22.849 − 311 =
  23. 23.470 − 242 =
  24. 24.737 − 359 =
  25. 25.826 − 643 =
  26. 26.941 − 507 =
  27. 27.297 + 426 =
  28. 28.373 + 246 =
  29. 29.839 − 263 =
  30. 30.875 − 529 =
  31. 31.505 + 386 =
  32. 32.391 + 312 =
  33. 33.767 + 489 =
  34. 34.695 + 287 =
  35. 35.628 − 334 =
  36. 36.472 + 321 =
  37. 37.670 + 685 =
  38. 38.596 − 182 =
  39. 39.718 + 289 =
  40. 40.719 − 553 =

Answer key

  1. 370
  2. 485
  3. 714
  4. 733
  5. 564
  6. 676
  7. 818
  8. 141
  9. 561
  10. 857
  11. 577
  12. 757
  13. 706
  14. 545
  15. 822
  16. 308
  17. 732
  18. 532
  19. 124
  20. 843
  21. 811
  22. 538
  23. 228
  24. 378
  25. 183
  26. 434
  27. 723
  28. 619
  29. 576
  30. 346
  31. 891
  32. 703
  33. 1256
  34. 982
  35. 294
  36. 793
  37. 1355
  38. 414
  39. 1007
  40. 166

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