January 2017 Fiendish Function

The Fiendish Function posed during January 2017 had the following sample guesses and replies:

• GUESS
• REPLY
• 1
• 2
• 2
• 16
• 3
• 512
• 4
• 66
• 5
• 36
• 10
• 4

The rule was: "Square the number, then add 2 to the power of the digits together".

Suppose the guess was 11:

• Square the number, giving 121.
• Take the number's digits, giving 1, 2, 1
• Take 2 to the power of each digit, giving 2, 4, 2
• Add these together, giving 8.

So the result is 8.