The LINEST (or linear estimate) function in Excel sales forecasting uses formulas to calculate a regression equation and related statistics. This chart shows the information the Excel LINEST function will give you:

Column 1 Column 2
Row 1 The coefficient you multiply times the X values The intercept
Row 2 The standard error of the coefficient The standard error of the intercept
Row 3 The R-squared value, or coefficient of determination. The standard error of estimate
Row 4 The F-ratio The degrees of freedom
Row 5 The sum of squares for the regression The sum of squares for the residual