Why is an order of magnitude more free space required when updating an Android application than the size of the application?

Question

Android

There is a HTC One S phone.
Android version 4.1.1 (latest official firmware)
Free Internal/App storage: 290MB
Free Phone storage: 4GB
Facebook application is installed on internal storage.
When an update comes out, the Play Market indicates that the size of the update is 26MB, that is, 11 times less than there is free space.
When trying to update during the installation phase, an "insufficient storage" error occurs.
After some shamanism, I managed to increase the free space in Internal Storage to 400 MB. After that, it was possible to update the Facebook application.
In this regard, it is very curious to understand what it is? Is it Android specific or is it HTC firmware specific or does the Facebook app need that much space to install?

Answer 1

Well, specifically for your numbers, the math is strange, but in general, installing a droid application requires 3 times more space than the application itself weighs. Somewhere like this:
- google cache - where the APK was downloaded
- archiver cache - temporary unpacking of APK
- target folder - the application is installed there
I'm not sure about the second point, I read this alignment about android 2 versions.