Nuns in their Cells

Classic Problem

There are $8$ nuns, one in each cell, making a total of $3$ nuns along each side of the courtyard:

How can they be arranged so there are $4$ nuns along each side?

Solution

Sources

• c. 1500: Fra Luca Pacioli: De Viribus Quantitatis
• 1992: David Wells: Curious and Interesting Puzzles ... (previous) ... (next): The Nuns in their Cells: $95$