Bloomberg
It's hard to plan for retirement, and one of the trickiest questions is: How much should I save?
The honest answer is: It depends. "The best-laid plans can be undone by a messy divorce, a disabling disease, or a stock market crash," Jonathan Skinner, a professor of economics at Dartmouth College, wrote in a study on the topic. Your future health-care expenses are almost impossible to predict, for example, especially as Congress considers big changes to the system.