How many 6 digit telephone numbers can be formed if each number starts with 35 and no digit appears more than once?
Pick one.
A) 720	B) 360	C) 1420	D) 1680	E) None of these
Explanation :   The first two places can only be filled by 3 and 5 respectively and there is only 1 way   of doing this   Given that no digit appears more than once. Hence we have 8 digits remaining(0,1,2,4,6,7,8,9)   So, the next 4 places can be filled with the remaining 8 digits in 8P4 ways   Total number of ways = 8P4 = 8 x 7 x 6 x 5 = 1680. Answer : Option 1680
<result>D</result>
How many 6 digit telephone numbers can be formed if each number starts with 35 and no digit appears more than once?