## April 2017 Fiendish Function

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

- 1
- 1
- 2
- 11
- 3
- 2
- 4
- 12
- 5
- 111
- 10
- 1111

The rule was: "Write the number in binary, then express as the number of '1's followed by the number of '0's, and so on".

Suppose the guess was 39:

- Write it in binary, giving 100111.
- Then express as the number of '1's followed by the number of '0's, and so on, giving 123.

So the result is 123.

## Earlier answers

Here are the answers to the Fiendish Functions posted in earlier months: