qc is a command line tool that calculates in-line math expressions with no pipes or command line tricks. The result of the calculation is displayed in the the command line and automatically copied to the clipboard for easy of use.

A handy way to use Python’s maths library at the command line.

Latte is a Mac OS X application that uses such Web engines as CodeCogs and Google Chart to typeset formulas written in LaTeX. Formulas can be dragged to other applications (e.g. Keynote, Pages) and, in the case of PDF formulas, scaled to an arbitrary size. Both the LaTeX input and the rendered output can be saved onto your local disk, making it easy to build a library of formulas.

The ‘num-utils’ are a set of programs for dealing with numbers from the Unix command line. Much like the other Unix command line utilities like grep, awk, sort, cut, etc. these utilities work on data from both standard in and data from files.

"bc is an arbitrary precision numeric processing language." I’m not even sure what that means, but can report that bc also works well as a command line calculator for basic arithmetic.