June 2017 Fiendish Function

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

  • GUESS
  • REPLY
  • 1
  • 4
  • 2
  • 16
  • 3
  • 256
  • 4
  • 66
  • 5
  • 12
  • 10
  • 8

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

Suppose the guess was 15:

  • Take the number's digits, giving 1, 5
  • Take 2 to the power of each digit, giving 2, 32
  • Add these together, giving 34.
  • Take the number's digits, giving 3, 4
  • Take 2 to the power of each digit, giving 8, 16
  • Add these together, giving 24.

So the result is 24.