Problem #PRU-102999

Problemas Álgebra y aritmética Aritmética. Matemáticas mentales Matemáticas discretas Combinatoria

Problem

Deep in a forest there is a small town of talking animals. Elephant, Crocodile, Rabbit, Monkey, Bear, Heron and Fox are friends. They each have a landline telephone and each two telephones are connected by a wire. How many wires were required?