10periodic file should look like this:
In this file, the various lines has different meaning as given below:
If this is set to "0" then it means that automatic update has been disabled.
If it is set to something other than "0" then it would imply the number of days for automatic update. e.g. setting it to "1" implies that your system will automatically update everyday.
If this is set to "0" then it means that automatic downloading of packages have been disabled.
But setting it to "1" = enable auto download package.
APT::Periodic::AutocleanInterval can have "0" or other number specifying the number of days for auto clean interval.
You can also have another entry;
APT::Periodic::Unattended-Upgrade. Setting it "0" will disable the automatic upgrade and "1" will enable the automatic upgrade.
I posted this answer because I thought your OS is Ubuntu. I'm not sure whether the
10periodic file in Elementary OS looks like this or not. If not then my answer would be useless.