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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 558 · 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. 1.230 + 238 =
  2. 2.671 − 121 =
  3. 3.391 + 193 =
  4. 4.504 − 134 =
  5. 5.578 − 353 =
  6. 6.740 − 566 =
  7. 7.270 + 421 =
  8. 8.578 − 211 =
  9. 9.418 + 191 =
  10. 10.803 − 533 =
  11. 11.579 + 245 =
  12. 12.516 − 328 =
  13. 13.545 − 187 =
  14. 14.966 − 566 =
  15. 15.564 − 204 =
  16. 16.505 − 321 =
  17. 17.646 − 374 =
  18. 18.675 − 266 =
  19. 19.319 + 175 =
  20. 20.606 − 307 =
  21. 21.308 + 639 =
  22. 22.520 − 361 =
  23. 23.292 + 182 =
  24. 24.374 + 464 =
  25. 25.285 + 531 =
  26. 26.868 − 425 =
  27. 27.617 − 137 =
  28. 28.697 − 196 =
  29. 29.755 + 115 =
  30. 30.341 + 551 =
  31. 31.496 − 141 =
  32. 32.187 + 516 =
  33. 33.867 − 688 =
  34. 34.240 + 621 =
  35. 35.434 − 306 =
  36. 36.464 + 571 =
  37. 37.468 + 681 =
  38. 38.821 − 591 =
  39. 39.552 − 363 =
  40. 40.650 + 458 =

Answer key

  1. 468
  2. 550
  3. 584
  4. 370
  5. 225
  6. 174
  7. 691
  8. 367
  9. 609
  10. 270
  11. 824
  12. 188
  13. 358
  14. 400
  15. 360
  16. 184
  17. 272
  18. 409
  19. 494
  20. 299
  21. 947
  22. 159
  23. 474
  24. 838
  25. 816
  26. 443
  27. 480
  28. 501
  29. 870
  30. 892
  31. 355
  32. 703
  33. 179
  34. 861
  35. 128
  36. 1035
  37. 1149
  38. 230
  39. 189
  40. 1108

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