### Pentominous by Murat Can Tonta

PDF

or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a composite mode for line/edge drawing and a letter entry mode.)

Theme: Roman Numerals

Author/Opus: This is the 11th puzzle from guest contributor Murat Can Tonta.

Rules: Divide the grid into 20 pentominoes so that no two pentominoes of the same shape (including rotations/reflections) share an edge. A cell with a letter in it must be part of the pentomino shape normally associated with that letter. An inventory of possible pentominoes is given below the puzzle.

Answer String: Enter the letter associated with the pentomino occupying each cell in the marked rows from left to right, separating the groups with a comma. Use CAPITAL LETTERS!

Time Standards (highlight to view): Grandmaster = 3:45, Master = 5:15, Expert = 10:30

Solution: PDF; a solution video is available here.

• Aaron Chan says:

I really loved the way this one solves. The way that it seems to have so many possibilities until you narrow it down is simply elegant.

• Bryce Herdt says:

I’ve been sitting on the idea of pentominoes-as-Roman-numerals for a while now. I want to involve the actual values, but that’s as much as I’ve figured out mechanically. Still, I’ve determined UPW can take the values of CDM with just the least bit of confusion.

• Nikolai says:

Nice puzzle, thanks 🙂

• skynet says:

14:27

• Carl W says:

5:58 I think that’s the closest I’ve gotten to expert time to date. (And I probably could have shaved a fair amount off by not writing a letter into every cell nor outlining every pentomino).

• James Lewis says: