"Krunner operates independently of the Plasma desktop system as
a standalone application. It includes a ton of features that make
it useful beyond simple command launching. It has retained many of
the features present in KDE 3 and greatly expanded them. We would
fail to do it justice if we did not give it a top ten list.
Krunner calculatorDo you need to figure out how much money you have
left for groceries after subscribing to three MMORPGs? Just press
"Alt-F2" or right click on the desktop and press “run
command”. To use Krunner as a calculator, type the = sign and
then enter the equation. For example, type "=890*12", and it will
output a calculator icon and the answer: "10680". Simply select the
answer to calculate the next equation with it. KDE 3 had a similar
calculating feature that automatically opened Google’s
calculator. With this you can calculate multiple times without
leaving the Krunner window."