```Question 313953
There is a formula:  {{{log(b,a)=(ln a)/(ln b)}}}

According to this formula,
{{{log(2,18)= (ln 18)/(ln 2)}}}
{{{log(2,18)= 4.17 }}} approximately.

For additional help with Logarithms, please see my own website.  Click on my tutor name "rapaljer" anywhere in algebra.com.  There you will see the link to my Homepage.  Near the top of my Homepage, look for the link "Basic, Intermediate, and College Algebra: One Step at a Time."  Choose "College Algebra", and look for "Chapter 4" which is "Logarithms."   See Section 4.04, for more explanataion on this particular type of problem.  In this chapter, you will find my own non-traditional explanation of Logarithms, complete with examples, exercises, and ALL the answers.  Many of these exercises are also solved IN COLOR on my "Math in Living Color" pages that go along with these sections.

In addition, please see my FREE videos, which were in my own classes before I retired a few years ago.  To see the videos, look on my Homepage for the link "Rapalje Videos in Living Color."  Click on "College Algebra" and look for Logarithms Part I and Part II.  Part II is appropriate for this question.

Dr. Robert J. Rapalje, Retired
Seminole State College of Florida
Altamonte Springs Campus ```