Nautilus icon shows always a number

The icon always shows a number 3 at the right corner in green color. The number is being shown there for months and I don´t know how to remove it from there.
I have updated my ubuntu (and Nautilus) several times and the number in the Nautilus icon always remains. (Now I have 45.rc version of GNOME)
Any idea?

SOLVED. After a research, I found out that there is a notification list linked with this numbers. To show the list, you have to click on the date (above the desktop) and then push “clean all” button to remove all the notification numbers on icons.