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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 890 · 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. 1.430 + 118 =
  2. 2.599 + 638 =
  3. 3.868 − 492 =
  4. 4.861 − 666 =
  5. 5.185 + 279 =
  6. 6.729 + 652 =
  7. 7.215 + 167 =
  8. 8.819 − 564 =
  9. 9.433 − 283 =
  10. 10.778 + 234 =
  11. 11.940 − 458 =
  12. 12.552 − 188 =
  13. 13.700 − 383 =
  14. 14.539 − 272 =
  15. 15.279 + 225 =
  16. 16.547 − 187 =
  17. 17.291 + 239 =
  18. 18.699 + 319 =
  19. 19.133 + 521 =
  20. 20.872 − 429 =
  21. 21.589 + 254 =
  22. 22.458 + 269 =
  23. 23.623 − 243 =
  24. 24.956 − 176 =
  25. 25.373 + 283 =
  26. 26.764 + 204 =
  27. 27.786 − 121 =
  28. 28.486 + 359 =
  29. 29.654 − 446 =
  30. 30.302 + 193 =
  31. 31.532 − 202 =
  32. 32.464 − 161 =
  33. 33.615 − 233 =
  34. 34.534 − 301 =
  35. 35.129 + 211 =
  36. 36.927 − 793 =
  37. 37.922 − 371 =
  38. 38.475 + 197 =
  39. 39.280 + 245 =
  40. 40.750 + 601 =

Answer key

  1. 548
  2. 1237
  3. 376
  4. 195
  5. 464
  6. 1381
  7. 382
  8. 255
  9. 150
  10. 1012
  11. 482
  12. 364
  13. 317
  14. 267
  15. 504
  16. 360
  17. 530
  18. 1018
  19. 654
  20. 443
  21. 843
  22. 727
  23. 380
  24. 780
  25. 656
  26. 968
  27. 665
  28. 845
  29. 208
  30. 495
  31. 330
  32. 303
  33. 382
  34. 233
  35. 340
  36. 134
  37. 551
  38. 672
  39. 525
  40. 1351

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