Geometry

Question Analysis
This question is about permutations where repetition is permitted.
The key is to determine the total number of available characters () and the number of characters in the password (), and then apply the formula .

Key Concept Explanation
When repetition is allowed in a permutation problem, for each position in the sequence (here, each character in the password), there are choices.
The formula gives the total number of possible arrangements.

Step - by - Step Solution
There are 10 digits (0 - 9) and 26 letters (A - Z, case - insensitive), so the total number of available characters .
The password has