Percentage increase and decrease

[sergeevabc]

Dear @hanna-kn,
sometimes I manage to reduce something bloated, for example, reduce the image weight without noticeable loss of quality, and then I want to express the success in percentages.

Percentage decrease calculator says here that the image weight was reduced by 84%.
What do I need to enter after qalc.exe to get that value?
I tried qalc.exe percentage difference between 406958 and 66873.

[hanna-kn]

The GUIs (qalculate-gtk and qalculate-qt) provides a dialog for simple percentage calculation.

With qalc you will have to resort to simple division, e.g. 64949/406958 − 1. This will return −0.84. Multiply with 100 or use to % (or ->%), e.g. qalc 64949/406958-1 to %, to get the result in percent.