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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 972 · 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. 1.784 − 658 =
  2. 2.837 − 521 =
  3. 3.332 + 615 =
  4. 4.440 − 164 =
  5. 5.643 − 436 =
  6. 6.622 + 322 =
  7. 7.481 + 658 =
  8. 8.588 + 293 =
  9. 9.840 − 582 =
  10. 10.503 − 243 =
  11. 11.660 + 243 =
  12. 12.539 + 438 =
  13. 13.346 + 493 =
  14. 14.547 − 151 =
  15. 15.359 + 537 =
  16. 16.779 + 508 =
  17. 17.172 + 262 =
  18. 18.745 − 599 =
  19. 19.241 + 595 =
  20. 20.968 − 301 =
  21. 21.830 − 393 =
  22. 22.976 − 571 =
  23. 23.523 − 271 =
  24. 24.614 − 438 =
  25. 25.192 + 235 =
  26. 26.608 − 463 =
  27. 27.214 + 418 =
  28. 28.906 − 221 =
  29. 29.577 + 375 =
  30. 30.644 + 636 =
  31. 31.975 − 308 =
  32. 32.342 + 425 =
  33. 33.723 − 121 =
  34. 34.429 − 257 =
  35. 35.452 + 178 =
  36. 36.275 + 423 =
  37. 37.783 + 478 =
  38. 38.481 + 666 =
  39. 39.432 − 199 =
  40. 40.568 − 288 =

Answer key

  1. 126
  2. 316
  3. 947
  4. 276
  5. 207
  6. 944
  7. 1139
  8. 881
  9. 258
  10. 260
  11. 903
  12. 977
  13. 839
  14. 396
  15. 896
  16. 1287
  17. 434
  18. 146
  19. 836
  20. 667
  21. 437
  22. 405
  23. 252
  24. 176
  25. 427
  26. 145
  27. 632
  28. 685
  29. 952
  30. 1280
  31. 667
  32. 767
  33. 602
  34. 172
  35. 630
  36. 698
  37. 1261
  38. 1147
  39. 233
  40. 280

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