Question 1117825
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1.  The number of all 4-letter words written using the alphabet of 20 symbols (from A to T)  is  {{{20^4}}}.


2.  The number of all 4-letter words written using the alphabet of 19 symbols (from B to T) is  {{{19^4}}}.


3.  The difference  {{{20^4}}} - {{{19^4}}}  represents exactly the number of all words of the inhabitants of the island of Jumble.


    {{{20^4}}} - {{{19^4}}} = 29679.
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Solved.