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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 3 · 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. 1.732 − 492 =
  2. 2.609 − 156 =
  3. 3.606 − 321 =
  4. 4.518 + 293 =
  5. 5.436 + 488 =
  6. 6.336 + 192 =
  7. 7.689 + 545 =
  8. 8.873 − 762 =
  9. 9.770 + 341 =
  10. 10.541 − 303 =
  11. 11.143 + 371 =
  12. 12.844 − 462 =
  13. 13.453 + 621 =
  14. 14.789 − 189 =
  15. 15.722 + 476 =
  16. 16.666 + 497 =
  17. 17.728 + 131 =
  18. 18.446 − 175 =
  19. 19.771 − 433 =
  20. 20.490 + 579 =
  21. 21.415 + 647 =
  22. 22.376 + 271 =
  23. 23.407 + 341 =
  24. 24.547 + 381 =
  25. 25.581 − 362 =
  26. 26.658 + 447 =
  27. 27.477 + 166 =
  28. 28.521 − 195 =
  29. 29.473 − 117 =
  30. 30.828 − 653 =
  31. 31.253 + 253 =
  32. 32.573 − 251 =
  33. 33.166 + 476 =
  34. 34.646 − 428 =
  35. 35.977 − 165 =
  36. 36.251 + 306 =
  37. 37.864 − 597 =
  38. 38.195 + 556 =
  39. 39.339 + 548 =
  40. 40.295 + 121 =

Answer key

  1. 240
  2. 453
  3. 285
  4. 811
  5. 924
  6. 528
  7. 1234
  8. 111
  9. 1111
  10. 238
  11. 514
  12. 382
  13. 1074
  14. 600
  15. 1198
  16. 1163
  17. 859
  18. 271
  19. 338
  20. 1069
  21. 1062
  22. 647
  23. 748
  24. 928
  25. 219
  26. 1105
  27. 643
  28. 326
  29. 356
  30. 175
  31. 506
  32. 322
  33. 642
  34. 218
  35. 812
  36. 557
  37. 267
  38. 751
  39. 887
  40. 416

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