476. Digital Root Parity

Given a positive integer n, calculate its digital root. The digital root is the single-digit value obtained by repeatedly summing the digits of the number until only one digit remains. Return true if the resulting digital root is even, and false otherwise.

Example:
Input: n = 38
Output: true
Explanation: 3 + 8 = 11, 1 + 1 = 2. Since 2 is even, return true.

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