**Logarithms**

We consider logarithms with three different bases:

basee(natural logarithms),base 10, andbasebother thaneor 10, where 0 <bandb1.

Recall that the domain of a logarithm function consists
of all real numbers *x* > 0.

Press **MENU 1** to select the RUN-MAT screen.

**Base e**

Simply
use the **ln** (natural logarithm) key. For example, to calculate ln(17), press

ln 1 7 ) EXE

**Base 10**

Simply
use the **log** (common logarithm) key. For example, to calculate log(17),
press

log 1 7 ) EXE

**Other Bases**

For
logarithmic bases other than *e* or 10, one must apply the change of base
formula to convert to base *e*:

Hence, to determine log_{5}(17), note that log_{5}(17) = ln(17)/ln(5).
Here, log_{5}(17) 1.76.