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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 260 · 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. 1.159 + 171 =
  2. 2.728 + 485 =
  3. 3.921 − 539 =
  4. 4.750 − 581 =
  5. 5.520 + 314 =
  6. 6.358 + 155 =
  7. 7.767 − 223 =
  8. 8.700 + 688 =
  9. 9.236 + 689 =
  10. 10.705 − 443 =
  11. 11.560 + 301 =
  12. 12.354 + 573 =
  13. 13.312 + 339 =
  14. 14.692 + 526 =
  15. 15.539 − 311 =
  16. 16.428 − 211 =
  17. 17.596 + 589 =
  18. 18.690 + 341 =
  19. 19.748 − 359 =
  20. 20.317 + 591 =
  21. 21.379 + 193 =
  22. 22.751 + 582 =
  23. 23.634 + 264 =
  24. 24.931 − 809 =
  25. 25.603 − 421 =
  26. 26.815 − 292 =
  27. 27.613 − 406 =
  28. 28.490 − 157 =
  29. 29.918 − 224 =
  30. 30.768 − 444 =
  31. 31.554 − 408 =
  32. 32.170 + 508 =
  33. 33.522 + 375 =
  34. 34.461 + 226 =
  35. 35.535 + 191 =
  36. 36.851 − 398 =
  37. 37.574 − 112 =
  38. 38.285 + 687 =
  39. 39.672 + 213 =
  40. 40.773 − 269 =

Answer key

  1. 330
  2. 1213
  3. 382
  4. 169
  5. 834
  6. 513
  7. 544
  8. 1388
  9. 925
  10. 262
  11. 861
  12. 927
  13. 651
  14. 1218
  15. 228
  16. 217
  17. 1185
  18. 1031
  19. 389
  20. 908
  21. 572
  22. 1333
  23. 898
  24. 122
  25. 182
  26. 523
  27. 207
  28. 333
  29. 694
  30. 324
  31. 146
  32. 678
  33. 897
  34. 687
  35. 726
  36. 453
  37. 462
  38. 972
  39. 885
  40. 504

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