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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 216 · 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. 1.509 − 248 =
  2. 2.428 − 281 =
  3. 3.397 + 669 =
  4. 4.598 + 323 =
  5. 5.524 − 403 =
  6. 6.358 + 357 =
  7. 7.633 + 298 =
  8. 8.859 − 356 =
  9. 9.778 − 461 =
  10. 10.180 + 242 =
  11. 11.205 + 523 =
  12. 12.578 − 209 =
  13. 13.236 + 659 =
  14. 14.836 − 521 =
  15. 15.222 + 118 =
  16. 16.550 − 431 =
  17. 17.648 + 172 =
  18. 18.720 − 178 =
  19. 19.733 + 632 =
  20. 20.219 + 505 =
  21. 21.469 + 434 =
  22. 22.193 + 506 =
  23. 23.396 + 513 =
  24. 24.457 − 245 =
  25. 25.519 − 419 =
  26. 26.255 + 332 =
  27. 27.440 − 227 =
  28. 28.543 − 403 =
  29. 29.645 − 516 =
  30. 30.673 − 121 =
  31. 31.649 + 187 =
  32. 32.356 + 201 =
  33. 33.143 + 527 =
  34. 34.628 − 192 =
  35. 35.777 − 165 =
  36. 36.856 − 115 =
  37. 37.729 − 186 =
  38. 38.195 + 518 =
  39. 39.153 + 436 =
  40. 40.522 + 122 =

Answer key

  1. 261
  2. 147
  3. 1066
  4. 921
  5. 121
  6. 715
  7. 931
  8. 503
  9. 317
  10. 422
  11. 728
  12. 369
  13. 895
  14. 315
  15. 340
  16. 119
  17. 820
  18. 542
  19. 1365
  20. 724
  21. 903
  22. 699
  23. 909
  24. 212
  25. 100
  26. 587
  27. 213
  28. 140
  29. 129
  30. 552
  31. 836
  32. 557
  33. 670
  34. 436
  35. 612
  36. 741
  37. 543
  38. 713
  39. 589
  40. 644

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