Generally, one side would come up with their idea of the number and state their reasoning, the other side would do the same, and the judge looks at their reason

Generally, one side would come up with their idea of the number and state their reasoning, the other side would do the same, and the judge looks at their reasoning and decides what makes sense. This requires a lot of work to estimate and reason and argue and adjudicate, you're not going to get a napkin math answer on an internet forum.