Plasma/Krunner
Krunner
Krunner as a calculator
You can use Krunner as an efficient calculator. It's very easy to use too. Just press Alt+F2 and type the expression you want to evaluate such as 32*12= or =32*12 (You can put the = sign before or after the expression).
It is possible to evaluate more sophisticated expressions such as:
=sqrt(4) + 32 * sin(60)