January 2018 Fiendish Function

The Fiendish Function posed during January 2018 had the following sample guesses and replies:

  • GUESS
  • REPLY
  • 1
  • 2
  • 2
  • 9
  • 3
  • 28
  • 4
  • 65
  • 5
  • 126
  • 10
  • 2

The rule was: "Add the cubes of the number's digits together, then add one".

Suppose the guess was 23:

  • Take the number's digits, giving 2, 3
  • Cube them, giving 8, 27
  • Add these together, giving 35.
  • Add one, giving 36.

So the result is 36.