Henry Ernest Dudeney/Puzzles and Curious Problems/278 - The Thirty-Six Letter Puzzle

Puzzles and Curious Problems by Henry Ernest Dudeney: $278$

The Thirty-Six Letter Puzzle

If you try to fill up this square by repeating the letters $A$, $B$, $C$, $D$, $E$, $F$,

so that no $A$ shall be in a line across, downwards, or diagonally, with another $A$,

no $B$ with another $B$, no $C$ with another $C$, and so on,

you will find that it is impossible to get in all the $36$ letters under these conditions.

The puzzle is to place as many letters as possible.

Sources

• 1932: Henry Ernest Dudeney: Puzzles and Curious Problems ... (previous) ... (next): Combination and Group Problems: $278$. -- The Thirty-Six Letter Puzzle
• 1968: Henry Ernest Dudeney: 536 Puzzles & Curious Problems ... (previous) ... (next): Combinatorial & Topological Problems: Miscellaneous Combinatorial Puzzles: $461$. The Thirty-Six Letter Puzzle