A code consists of $6$ characters. The first $3$ characters of the code consists of $3$ digits chose

Question

A code consists of $6$ characters. The first $3$ characters of the code consists of $3$ digits chosen from $\left\{ 1,\,\,2,\,\,3,\,\,4,\,\,5,\,\,6 \right\}$. The last $3$ characters of the code consists of $3$ letters chosen from $\left\{ A,\,\,B,\,\,C,\,\,D,\,\,E,\,\,F,\,\,G,\,\,H \right\}$. How many codes can be formed if repetitions are not allowed? Now suppose that repetitions are allowed. Find the number of codes that contain the digit $5$ exactly once and the letter $H$ exactly twice. have $2$ as its first character or $H$ as its sixth character, but not both.

Accepted Answer

40 320; 1575; 27 648

N2017 H1 Q8 [Modified]

N2017 H1 Q8 [Modified]

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