Three pens with three pigs each, one large pen surrounding the other pens. The small pens hold three pigs - an odd number - and the large pen holds nine pigs - an odd number - and three pens.

Originally posted by Shallow Blue Three pens with three pigs each, one large pen surrounding the other pens. The small pens hold three pigs - an odd number - and the large pen holds nine pigs - an odd number - and three pens.

Originally posted by Shallow Blue Three pens with three pigs each, one large pen surrounding the other pens. The small pens hold three pigs - an odd number - and the large pen holds nine pigs - an odd number - and three pens.

Richard

Alternatively, you can build normal pens and have two pigs in three of the pens and three in the fourth. Two is an odd number, because it's the only even prime. 😉