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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 85 · 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. 1.442 + 168 =
  2. 2.917 − 416 =
  3. 3.541 − 143 =
  4. 4.324 + 544 =
  5. 5.402 + 397 =
  6. 6.430 + 664 =
  7. 7.763 − 622 =
  8. 8.535 + 124 =
  9. 9.534 + 655 =
  10. 10.760 + 659 =
  11. 11.490 − 183 =
  12. 12.175 + 212 =
  13. 13.564 − 159 =
  14. 14.639 + 593 =
  15. 15.413 + 568 =
  16. 16.770 + 595 =
  17. 17.384 + 247 =
  18. 18.446 + 183 =
  19. 19.699 + 251 =
  20. 20.872 − 467 =
  21. 21.311 + 336 =
  22. 22.686 + 289 =
  23. 23.869 − 132 =
  24. 24.649 − 223 =
  25. 25.637 + 581 =
  26. 26.459 + 541 =
  27. 27.442 − 245 =
  28. 28.260 + 373 =
  29. 29.470 + 228 =
  30. 30.505 − 252 =
  31. 31.493 + 651 =
  32. 32.355 + 178 =
  33. 33.223 + 321 =
  34. 34.150 + 168 =
  35. 35.642 − 488 =
  36. 36.470 + 459 =
  37. 37.596 − 437 =
  38. 38.487 + 159 =
  39. 39.972 − 345 =
  40. 40.729 − 123 =

Answer key

  1. 610
  2. 501
  3. 398
  4. 868
  5. 799
  6. 1094
  7. 141
  8. 659
  9. 1189
  10. 1419
  11. 307
  12. 387
  13. 405
  14. 1232
  15. 981
  16. 1365
  17. 631
  18. 629
  19. 950
  20. 405
  21. 647
  22. 975
  23. 737
  24. 426
  25. 1218
  26. 1000
  27. 197
  28. 633
  29. 698
  30. 253
  31. 1144
  32. 533
  33. 544
  34. 318
  35. 154
  36. 929
  37. 159
  38. 646
  39. 627
  40. 606

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