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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 668 · 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. 1.275 + 161 =
  2. 2.628 − 504 =
  3. 3.986 − 765 =
  4. 4.617 + 184 =
  5. 5.473 − 197 =
  6. 6.449 + 553 =
  7. 7.893 − 521 =
  8. 8.596 − 301 =
  9. 9.644 − 168 =
  10. 10.669 + 457 =
  11. 11.481 + 405 =
  12. 12.554 − 162 =
  13. 13.453 − 153 =
  14. 14.226 + 276 =
  15. 15.486 + 198 =
  16. 16.419 − 166 =
  17. 17.456 + 142 =
  18. 18.269 + 386 =
  19. 19.621 + 524 =
  20. 20.408 + 351 =
  21. 21.415 + 641 =
  22. 22.425 + 373 =
  23. 23.151 + 249 =
  24. 24.437 + 176 =
  25. 25.478 + 441 =
  26. 26.858 − 397 =
  27. 27.547 − 368 =
  28. 28.872 − 611 =
  29. 29.942 − 125 =
  30. 30.534 − 151 =
  31. 31.534 + 188 =
  32. 32.637 − 182 =
  33. 33.578 − 162 =
  34. 34.806 − 288 =
  35. 35.939 − 766 =
  36. 36.952 − 432 =
  37. 37.810 − 466 =
  38. 38.534 + 382 =
  39. 39.799 − 541 =
  40. 40.959 − 569 =

Answer key

  1. 436
  2. 124
  3. 221
  4. 801
  5. 276
  6. 1002
  7. 372
  8. 295
  9. 476
  10. 1126
  11. 886
  12. 392
  13. 300
  14. 502
  15. 684
  16. 253
  17. 598
  18. 655
  19. 1145
  20. 759
  21. 1056
  22. 798
  23. 400
  24. 613
  25. 919
  26. 461
  27. 179
  28. 261
  29. 817
  30. 383
  31. 722
  32. 455
  33. 416
  34. 518
  35. 173
  36. 520
  37. 344
  38. 916
  39. 258
  40. 390

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