Microsoft excel provides a very useful feature-----formula tracer.
Many people use functions in excel. Sometimes, you will use output of a function as input of another function. This is called nested function. When build nested function by too many levels, you will get lost in finding the variables which contribute to the final results. So, the excel provides us formula tracer. You just need pick the result which you are interested in. Then, click function tracer in formula tab. The arrows showing the relationship between dependent variables and independent variables appears. That's miraculous!
