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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 826 · 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. 1.384 + 413 =
  2. 2.885 − 182 =
  3. 3.425 + 257 =
  4. 4.947 − 327 =
  5. 5.229 + 572 =
  6. 6.780 + 383 =
  7. 7.871 − 408 =
  8. 8.509 + 334 =
  9. 9.157 + 377 =
  10. 10.655 − 293 =
  11. 11.387 + 146 =
  12. 12.656 − 403 =
  13. 13.389 + 412 =
  14. 14.555 + 641 =
  15. 15.414 − 132 =
  16. 16.419 − 133 =
  17. 17.784 + 424 =
  18. 18.606 + 591 =
  19. 19.498 − 195 =
  20. 20.789 + 245 =
  21. 21.648 − 196 =
  22. 22.499 − 307 =
  23. 23.552 + 568 =
  24. 24.685 − 494 =
  25. 25.609 − 201 =
  26. 26.599 − 454 =
  27. 27.417 − 228 =
  28. 28.532 + 226 =
  29. 29.378 + 348 =
  30. 30.496 − 333 =
  31. 31.467 − 174 =
  32. 32.740 + 294 =
  33. 33.328 + 291 =
  34. 34.293 + 543 =
  35. 35.805 − 374 =
  36. 36.891 − 335 =
  37. 37.638 − 209 =
  38. 38.545 + 252 =
  39. 39.895 − 361 =
  40. 40.752 + 621 =

Answer key

  1. 797
  2. 703
  3. 682
  4. 620
  5. 801
  6. 1163
  7. 463
  8. 843
  9. 534
  10. 362
  11. 533
  12. 253
  13. 801
  14. 1196
  15. 282
  16. 286
  17. 1208
  18. 1197
  19. 303
  20. 1034
  21. 452
  22. 192
  23. 1120
  24. 191
  25. 408
  26. 145
  27. 189
  28. 758
  29. 726
  30. 163
  31. 293
  32. 1034
  33. 619
  34. 836
  35. 431
  36. 556
  37. 429
  38. 797
  39. 534
  40. 1373

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