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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 328 · 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. 1.557 − 217 =
  2. 2.942 − 594 =
  3. 3.215 + 666 =
  4. 4.600 + 341 =
  5. 5.940 − 279 =
  6. 6.827 − 408 =
  7. 7.219 + 641 =
  8. 8.321 + 368 =
  9. 9.297 + 512 =
  10. 10.527 − 155 =
  11. 11.431 + 585 =
  12. 12.817 − 319 =
  13. 13.927 − 362 =
  14. 14.747 + 397 =
  15. 15.348 + 211 =
  16. 16.365 + 124 =
  17. 17.703 − 413 =
  18. 18.516 − 155 =
  19. 19.183 + 162 =
  20. 20.498 + 462 =
  21. 21.449 − 159 =
  22. 22.230 + 618 =
  23. 23.743 + 395 =
  24. 24.650 + 489 =
  25. 25.509 + 559 =
  26. 26.460 − 303 =
  27. 27.175 + 199 =
  28. 28.930 − 122 =
  29. 29.774 + 204 =
  30. 30.215 + 365 =
  31. 31.699 + 132 =
  32. 32.740 − 426 =
  33. 33.505 − 219 =
  34. 34.674 − 226 =
  35. 35.165 + 532 =
  36. 36.234 + 641 =
  37. 37.770 − 554 =
  38. 38.751 + 478 =
  39. 39.627 + 463 =
  40. 40.171 + 266 =

Answer key

  1. 340
  2. 348
  3. 881
  4. 941
  5. 661
  6. 419
  7. 860
  8. 689
  9. 809
  10. 372
  11. 1016
  12. 498
  13. 565
  14. 1144
  15. 559
  16. 489
  17. 290
  18. 361
  19. 345
  20. 960
  21. 290
  22. 848
  23. 1138
  24. 1139
  25. 1068
  26. 157
  27. 374
  28. 808
  29. 978
  30. 580
  31. 831
  32. 314
  33. 286
  34. 448
  35. 697
  36. 875
  37. 216
  38. 1229
  39. 1090
  40. 437

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