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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 198 · 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. 1.335 + 651 =
  2. 2.331 + 159 =
  3. 3.541 − 183 =
  4. 4.878 − 479 =
  5. 5.761 + 407 =
  6. 6.415 + 356 =
  7. 7.423 − 167 =
  8. 8.539 + 448 =
  9. 9.158 + 171 =
  10. 10.477 − 276 =
  11. 11.473 − 293 =
  12. 12.258 + 341 =
  13. 13.664 + 133 =
  14. 14.305 + 559 =
  15. 15.626 + 612 =
  16. 16.307 + 481 =
  17. 17.940 − 149 =
  18. 18.643 + 621 =
  19. 19.708 − 553 =
  20. 20.398 + 661 =
  21. 21.516 − 117 =
  22. 22.706 + 252 =
  23. 23.302 + 673 =
  24. 24.957 − 705 =
  25. 25.421 + 455 =
  26. 26.918 − 647 =
  27. 27.432 − 217 =
  28. 28.488 + 166 =
  29. 29.771 + 581 =
  30. 30.408 + 232 =
  31. 31.425 + 634 =
  32. 32.144 + 505 =
  33. 33.868 − 645 =
  34. 34.525 − 242 =
  35. 35.663 − 185 =
  36. 36.774 + 351 =
  37. 37.290 + 206 =
  38. 38.338 + 422 =
  39. 39.352 + 196 =
  40. 40.737 + 279 =

Answer key

  1. 986
  2. 490
  3. 358
  4. 399
  5. 1168
  6. 771
  7. 256
  8. 987
  9. 329
  10. 201
  11. 180
  12. 599
  13. 797
  14. 864
  15. 1238
  16. 788
  17. 791
  18. 1264
  19. 155
  20. 1059
  21. 399
  22. 958
  23. 975
  24. 252
  25. 876
  26. 271
  27. 215
  28. 654
  29. 1352
  30. 640
  31. 1059
  32. 649
  33. 223
  34. 283
  35. 478
  36. 1125
  37. 496
  38. 760
  39. 548
  40. 1016

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