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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 467 · 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. 1.220 + 313 =
  2. 2.534 + 491 =
  3. 3.632 − 294 =
  4. 4.206 + 383 =
  5. 5.161 + 174 =
  6. 6.572 + 657 =
  7. 7.691 + 552 =
  8. 8.162 + 578 =
  9. 9.696 − 542 =
  10. 10.736 + 362 =
  11. 11.684 + 408 =
  12. 12.168 + 122 =
  13. 13.473 + 651 =
  14. 14.936 − 187 =
  15. 15.614 − 353 =
  16. 16.765 + 563 =
  17. 17.844 − 375 =
  18. 18.597 − 455 =
  19. 19.833 − 365 =
  20. 20.608 + 147 =
  21. 21.875 − 422 =
  22. 22.911 − 137 =
  23. 23.483 + 583 =
  24. 24.839 − 285 =
  25. 25.637 − 118 =
  26. 26.528 − 308 =
  27. 27.813 − 591 =
  28. 28.286 + 303 =
  29. 29.163 + 239 =
  30. 30.691 − 194 =
  31. 31.134 + 561 =
  32. 32.480 − 317 =
  33. 33.387 + 252 =
  34. 34.260 + 451 =
  35. 35.555 + 658 =
  36. 36.676 − 348 =
  37. 37.681 − 231 =
  38. 38.685 − 335 =
  39. 39.954 − 661 =
  40. 40.802 − 207 =

Answer key

  1. 533
  2. 1025
  3. 338
  4. 589
  5. 335
  6. 1229
  7. 1243
  8. 740
  9. 154
  10. 1098
  11. 1092
  12. 290
  13. 1124
  14. 749
  15. 261
  16. 1328
  17. 469
  18. 142
  19. 468
  20. 755
  21. 453
  22. 774
  23. 1066
  24. 554
  25. 519
  26. 220
  27. 222
  28. 589
  29. 402
  30. 497
  31. 695
  32. 163
  33. 639
  34. 711
  35. 1213
  36. 328
  37. 450
  38. 350
  39. 293
  40. 595

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