Silly person. Just because it's not on the keyboard doesn't mean it's not there. Look in the catalog for log, or just type it in. >I'm not sure what you mean by "Log", is this base 10 or base e? >The TI-89 and TI-92+ plus does not have a base 10 key like the TI-85 and TI-86's >have. If you want log base 10 use a change of base formula: > >log(b)(x)=ln(x)/ln(b)