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In the English alphabet, there are 7 capital letters that look the same after being rotated 180∘. Those letters are H, I, N, O, S, X, and Z. How many different 3 letter "words" can be made from these letters such that when the word is rotated 180∘, the resulting word is the same?

  1. 👍
  2. 👎
  3. 👁
  4. ℹ️
  5. 🚩

4 answers

  1. Clearly the 1st and 3rd letter must be the same, but the middle can be any of the 7 letters

    number of ways = 7 x 7 x 1 = 49

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩
  2. SOS

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩
  3. It’s not right

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩
  4. It’s not right jishca

    1. 👍
    2. 👎
    3. ℹ️
    4. 🚩

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