Random amount of nodes with random connections assigned random weightings until something works best.

Not so sure it's possible for anyone to seriously claim to be able to explain the inner workings.

Biggest problem with these I can see is that there is more than one way to arrive at the given answer.

Simplistic analogy, let's say the equivalent nodes were represented by the value 20. Was this number a result of 5 * 4, 4 * 5, 10 * 2, 10 + 10 etc..

Right now, it doesn't matter, we're all just happy that 20 is correct and works for our use case. Maybe that will be good enough but I doubt it.