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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 206 · 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. 1.879 − 459 =
  2. 2.442 − 299 =
  3. 3.577 − 191 =
  4. 4.956 − 754 =
  5. 5.617 − 153 =
  6. 6.718 − 204 =
  7. 7.266 + 585 =
  8. 8.947 − 711 =
  9. 9.806 − 644 =
  10. 10.545 − 195 =
  11. 11.680 − 138 =
  12. 12.745 − 632 =
  13. 13.772 − 669 =
  14. 14.514 − 315 =
  15. 15.694 − 536 =
  16. 16.311 + 171 =
  17. 17.447 − 297 =
  18. 18.731 + 649 =
  19. 19.414 + 366 =
  20. 20.733 + 135 =
  21. 21.915 − 771 =
  22. 22.424 − 253 =
  23. 23.526 − 138 =
  24. 24.432 − 229 =
  25. 25.739 − 257 =
  26. 26.409 + 211 =
  27. 27.466 − 135 =
  28. 28.844 − 676 =
  29. 29.724 + 231 =
  30. 30.781 − 371 =
  31. 31.610 + 483 =
  32. 32.382 + 646 =
  33. 33.761 + 461 =
  34. 34.435 + 381 =
  35. 35.691 − 178 =
  36. 36.339 + 119 =
  37. 37.576 − 247 =
  38. 38.611 − 218 =
  39. 39.613 + 465 =
  40. 40.459 + 499 =

Answer key

  1. 420
  2. 143
  3. 386
  4. 202
  5. 464
  6. 514
  7. 851
  8. 236
  9. 162
  10. 350
  11. 542
  12. 113
  13. 103
  14. 199
  15. 158
  16. 482
  17. 150
  18. 1380
  19. 780
  20. 868
  21. 144
  22. 171
  23. 388
  24. 203
  25. 482
  26. 620
  27. 331
  28. 168
  29. 955
  30. 410
  31. 1093
  32. 1028
  33. 1222
  34. 816
  35. 513
  36. 458
  37. 329
  38. 393
  39. 1078
  40. 958

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