Problem 81 (difficulty: 1/10)


 (1)  How many word of length \(\displaystyle k\) can be created using the letters \(\displaystyle A, B, C, D, E, F, G\)?
 (2)  How many such word of length \(\displaystyle 7\) can be created without repeating a letter?
 (3)  How many such word of length \(\displaystyle 7\) can be created with the property that \(\displaystyle A\) and \(\displaystyle B\) are neighbors (no repetition)?

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