A customer forgets a foru-digit code for an Automatic Teller Machine (ATM) in a bank
Channel: Doubtnut
Date: 05/04/2020

A customer forgets a foru-digit code for an Automatic Teller Machine (ATM) in a bank. However, he remembers that this code consists of digits 3,5,6 and 9. Find the largest possible nuim,ber of trials necessary to obtain the correct code.