formula help

[James__S]

Hi

I have a formula in a spreadsheet which i need help to understand

This is the 1st part of a calculation. I understand the rest of the calculation except this natural logarithm

=((LN(D5/10)*-0.5179)+2.66)*D6

This is then the following
=((LN(temperature/10)*-0.5179)+2.66)*flow rate

Values plugged in
=((LN(200/10)*-0.5179)+2.66)*20000

Answer = 22170.2

Could someone offer some advise on how this formula works in excel?

Thanks

JS