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# How many 5-digit telephone numbers can be constructed using the digit 0 to 9 if each number starts with 67 and no digit appear more than once?

$\begin{array}{1 1}(A)\;226\\(B)\;326\\(C)\;336\\(D)\;436\end{array}$

There are 10 digits from 0 to 9
I place after 67 can be filled in 8 ways.
II place after 67 can be filled in 7 ways.
III place after 67 can be filled in 6 ways.
$\therefore$ No of telephone numbers that can be constructed.
$\Rightarrow 8\times 7\times 6$
$\Rightarrow 336$
Hence (C) is the correct answer.