On the calculus page, I've created a logarithm lesson, that will solve for any of the 3 pieces of the logarithm equation, base, exponent, or logarithm number.
For natural logarithms, you can enter "e" or "E" without the quotes as a base. Later on down the road, I'll build in variables, but I felt this was a starting point to build from.
It's searchable by logarithm, exponent, base, natural.
Please let me know of any enhancements or errors.