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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 892 · 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. 1.423 − 128 =
  2. 2.664 − 156 =
  3. 3.697 − 144 =
  4. 4.966 − 482 =
  5. 5.638 + 481 =
  6. 6.594 + 679 =
  7. 7.482 + 131 =
  8. 8.980 − 635 =
  9. 9.260 + 328 =
  10. 10.317 + 136 =
  11. 11.935 − 512 =
  12. 12.674 − 338 =
  13. 13.718 − 234 =
  14. 14.137 + 145 =
  15. 15.567 − 126 =
  16. 16.443 − 144 =
  17. 17.652 + 376 =
  18. 18.450 − 152 =
  19. 19.621 + 311 =
  20. 20.735 − 281 =
  21. 21.984 − 591 =
  22. 22.230 + 155 =
  23. 23.701 − 378 =
  24. 24.342 + 621 =
  25. 25.224 + 641 =
  26. 26.827 − 659 =
  27. 27.235 + 612 =
  28. 28.941 − 616 =
  29. 29.516 − 385 =
  30. 30.588 − 287 =
  31. 31.131 + 413 =
  32. 32.727 + 166 =
  33. 33.520 + 591 =
  34. 34.559 + 551 =
  35. 35.722 − 578 =
  36. 36.460 − 264 =
  37. 37.863 − 221 =
  38. 38.616 + 632 =
  39. 39.771 − 303 =
  40. 40.457 + 537 =

Answer key

  1. 295
  2. 508
  3. 553
  4. 484
  5. 1119
  6. 1273
  7. 613
  8. 345
  9. 588
  10. 453
  11. 423
  12. 336
  13. 484
  14. 282
  15. 441
  16. 299
  17. 1028
  18. 298
  19. 932
  20. 454
  21. 393
  22. 385
  23. 323
  24. 963
  25. 865
  26. 168
  27. 847
  28. 325
  29. 131
  30. 301
  31. 544
  32. 893
  33. 1111
  34. 1110
  35. 144
  36. 196
  37. 642
  38. 1248
  39. 468
  40. 994

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