I have a feeling that R^2 values in Excel are a bit off. I seem to be getting different values. For the same data set, the R-squared value that chart tool calculates is different from the value that the LINEST() worksheet function generates. What gives? The R-squared values were never right when I checked the Set Intercept = 0 box.

Why does Excel 2003 sometimes generate random numbers that are negative? I am trying to do a Monte Carlo simulation of option prices that expects a number from 0 to 1.