How do you evaluate ##ln (1/e)##?

It is ##-1##.

We apply the properties of the logarithm:

##ln(1/e)=ln(e^(-1))##

the first property is that the exponent "exit" and multiply the log

##ln(e^-1)=-ln(e)##

the second property is that the logarithm of the base is 1. The base of the natural logarithm is ##e## then

##-ln(e)=-1##.

In conclusion

##ln(1/e)=-1##.