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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 794 · 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. 1.205 + 677 =
  2. 2.327 + 376 =
  3. 3.447 − 263 =
  4. 4.519 + 171 =
  5. 5.205 + 221 =
  6. 6.631 + 159 =
  7. 7.433 − 171 =
  8. 8.706 + 376 =
  9. 9.873 − 157 =
  10. 10.650 + 397 =
  11. 11.662 + 252 =
  12. 12.764 + 543 =
  13. 13.826 − 631 =
  14. 14.834 − 225 =
  15. 15.909 − 466 =
  16. 16.701 − 406 =
  17. 17.448 − 329 =
  18. 18.588 + 223 =
  19. 19.785 + 561 =
  20. 20.426 + 631 =
  21. 21.461 + 326 =
  22. 22.702 + 407 =
  23. 23.794 − 276 =
  24. 24.804 − 288 =
  25. 25.813 − 546 =
  26. 26.606 − 362 =
  27. 27.181 + 519 =
  28. 28.131 + 463 =
  29. 29.988 − 411 =
  30. 30.229 + 322 =
  31. 31.918 − 729 =
  32. 32.206 + 593 =
  33. 33.641 − 226 =
  34. 34.725 − 163 =
  35. 35.199 + 429 =
  36. 36.918 − 561 =
  37. 37.928 − 332 =
  38. 38.438 − 152 =
  39. 39.478 + 221 =
  40. 40.410 + 322 =

Answer key

  1. 882
  2. 703
  3. 184
  4. 690
  5. 426
  6. 790
  7. 262
  8. 1082
  9. 716
  10. 1047
  11. 914
  12. 1307
  13. 195
  14. 609
  15. 443
  16. 295
  17. 119
  18. 811
  19. 1346
  20. 1057
  21. 787
  22. 1109
  23. 518
  24. 516
  25. 267
  26. 244
  27. 700
  28. 594
  29. 577
  30. 551
  31. 189
  32. 799
  33. 415
  34. 562
  35. 628
  36. 357
  37. 596
  38. 286
  39. 699
  40. 732

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