Geometry

Question Analysis
This question pertains to permutations where repetition of elements is allowed.
The key is to apply the formula , where represents the number of available symbols and is the number of symbols in the code.

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

Step - by - Step Solution
In this case,

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