If the password has 9 digits then there are 10P9 way to arrange 10 digits in 9 places or 10!/(10-9)!= 10! ways

If the password has 10 digits the there are 10P10 way to arrange 10 digits in 10 places or 10!/(10-10)!= 10! ways

SO the answer is 10!+10! = 2*10!, Hence B

Added OA

Thank you

A popular website requires users to create a password consisting of digits only. If no digit may be repeated and each password must be at least 9 digits long, how many passwords are possible?

A. 9! + 10!
B. 2 x 10!
C. 9! x 10!
D. 19!
E. 20!

Kudos for correct solution.

for 9 digit, possible no= 10.9.8.7.6.5.4.3.2=10!
for 10 digit, possible no =10.9.8.7.6.5.4.3.2.1=10!

Total= 10!+10!=2*10!

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