Question

What is the count of possible passwords if the characters in the passwords are all either letters or digits and the length of the password is 6 and it must contain at least one digit and one letter? (Assume all letters are lower case, so there are only 26 letters). Group of answer choices

Answer 1

1857866560

Step-by-step explanation:

10 digits + 26 letters = 36 possible combination for each of the character in the password.

Since the password has a length of 6, there are

`36 * 36 * 36 * 36 * 36 * 36 = 36^6 = 2176782336` possible password combination

Since we need to make sure there's at least 1 letter and 1 number in the password, we can subtract (remove) the above result by the cases where password is made up all letters and all numbers

All numbers:
`10^6 = 1000000` cases

All letters:
`26^6 = 308915776` cases

So the number of possible combination password where there's at least 1 letter and 1 number is:

`2176782336-1000000-308915776=1857866560\approx 1.86*10^9`