Hi
passwords consist of 4 digits followed by 3 letters. Each password cannot repeat a letter or number,
10 digits and 26 letters generates:
10·9·8· 7· 26· 25· 24
no password can be repeated.
To the nearest year, how many years of passwords exist?
3000 employees,changing passwords at the beginning of each month
(10·9·8·7·26·25·24)/(12·3000)