Question 247357
In the past, a local telephone number in the U.S. consisted of a sequence of
two letters followed by five digits. Three letters were associated with each number from 2 to 9 (just as in the standard telephone layout shown in the figure) so that each telephone number corresponded to a sequence of 7 digits. How many different sequences of 7 digits were possible?

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Assuming that both letters and digits can be repeated 
the number of sequences would be 26^2*8^2 = 43,264
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Cheers,
Stan H.