Open the worksheet that contains the chart.To display a greater number of digits, use one of the following methods: Method 1: Microsoft Office Excel 2007
The trendline equation and R-squared value are initially displayed as rounded to five digits. This article explains how to display more digits in the coefficients.
For some purposes, this may not be a sufficient number of significant figures. When you add a trendline to a chart, and then display the equation and R-squared value for the trendline, the equation shows only the first five digits of each coefficient.