Question

How many $6$ digit telephone numbers can be formed if each number starts with $06$ and no digit appears more than once

• A. $720$
• B. $1680$
• C. $360$
• D. $1420$

Answer 1

The correct option is B $1680$

$6$ digit telephone number

06 _ _ _ _

Out of 0,1,2,3,4,5,6,7,8,9 $6$ and $0$ have been already used.

Rest of the places can be filled in $8\times 7\times 6=1680$