Turn Num Lock key on

This can be done through 2 steps.

1. Install "numlockx" 
2. Edit the /etc/gdm/Init/Default file

Install numlockx through terminal using this command
sudo yum install numlockx

Edit the /etc/gdm/Init/Default file through Gedit using this command in a terminal
sudo gedit /etc/gdm/Init/Default

In the file which opens, above exit 0, paste the lines below

if [ -x /usr/bin/numlockx ]; then
/usr/bin/numlockx on
fi

Save the file and exit.

Next time you reboot, num lock will be on by default