trendline for arrays with missing data points

Dear experts,

I have a dataset which is an array of measurements with one data point missing.
When I plot a logarithmic trendline, I get a certain R-squared for the fit. Because I cannot leave this data point empty, I wonder - how exactly excel deals with this empty data point when calculating the fit? I've been trying to model it using the coefficients of the log fit (using the LINEST function) and still did not get the exact same R-squared.
I've already searched all the forums on the net and tried to "fill" the missing data by the auto fill function and using the TREND function on the array of data preceding the missing data point.
Below is an example of the data (8th data point is missing):

8.659048
31.61216
41.75575
47.64559
45.23398
52.12204
41.56181

50.9005
57.66537

The R-squared for the log fit is 0.84.

Thank you very much in advance!

Anna