Consider the following simple case: six letters and two wires.
You can't just say 6 * 5 * 4 * 3, because that would consider "wire 1 connects A to B / wire 2 connects C to D" and "wire 1 connects C to D / wire 2 connects A to B" as distinct choices while they are actually the same.
Consider the following simple case: six letters and two wires.
You can't just say 6 * 5 * 4 * 3, because that would consider "wire 1 connects A to B / wire 2 connects C to D" and "wire 1 connects C to D / wire 2 connects A to B" as distinct choices while they are actually the same.