You have ever wondered that where the apps are stored temporarily when they are downloaded from Google play store.
As it is known that installed applications are generally stored in data/app/ location.
For the downloaded apps, they were usually stored in /cache/download or /data/local directories in the earlier versions of Android.
However these days, temporary location is determined by the Download Provider service, and is generally found in /data/data/com.android.providers.downloads/cache directory.
It may vary depending on Android OS version which may be different for Android Lollipop or Marshmallow.
It may also be different if the smartphone manufacturer modified the OS like Samsung's TouchWiz or HTC's Sense.
Once the app is the installed, the file is deleted from the temporary location.