CleanMaster Junk Files

I have noticed this anomoly.. CleanMaster reports different amounts of junk files.

CleanMaster Process

Step 1: CleanMaster pops up (bottom right of screen) saying it has detected 1.61GB of junk files , click to delete now.

Step 2: After clicking the Clean button on the pop-up, CleanMaster runs a check and finds 1.9Gb of of junk files.

Step 3: Hitting Clean, it cleans 1.1Gb of junk files

So, it’s gone from 1.61GB to 1.9Gb to 1.1GB in the space of a minute.

Which Gb is correct and why the 3 different amounts?

PS: we really like CleanMaster