Powerful and easy to use desktop calculator - transitional

 Qalculate! is small and simple to use but with much power and versatility
 underneath. Features include customizable functions, units, arbitrary
 precision, plotting, and a graphical interface that uses a one-line
 fault-tolerant expression entry (although it supports optional traditional
 buttons).
 .
 This is a transitional package that can be removed once you installed
 qalculate-gtk.