In a math problem it is the final answer. It is the total. On a bill, it's what you really owe, after the taxes, the tip, parts and labor, and all the other stuff is worked in. "The bottom line" is what really matters. We make decisions based on our bottom line. But the bottom line is not always a number. It is not always money. Often, we forget that. All too often, we forget that there can be a huge difference between what something is worth, and what it costs. You can't put a price on everything. Some things are worth more than money.