A customer forgets a four-digit code for an automated teller machine (ATM) in a bank. However, he remembers that this code consists of digits 3, 5, 6, 9. Find the largest possible number of trials necessary to obtain the correct code.

Question

Philoid · Accepted Answer

Given: code consists of digits 3, 5, 6, 9.

To find: the largest possible number of trials necessary to obtain the correct code.

The customer remembers that this 4 digit code consists of digits 3, 5, 6, 9.

So the largest possible number of trials necessary to obtain the correct code=4!=4 × 3 × 2 × 1=24