According to this link:
Enable NumLock during startup
Enabling Numlock on startup can be done of several different ways. First install numlockx:
sudo apt-get install numlockx
Place command with init scripts
sudo sed -i 's|^exit 0.*$|# Numlock enable\n[ -x /usr/bin/numlockx ] \&\& numlockx on\n\nexit 0|' /etc/rc.local
Enabling NumLock from startx
If you are not using a graphical display manager then add the following line to /etc/X11/xinit/xinitrc
/usr/bin/numlockx on
Enabling NumLock for Virtual Consoles (TTYs)
If you use the virtual consoles regularly, then you will quite likely want to have numlock on for the TTYs after boot up. The status of numlock/scroll-lock/capslock can be manipulated with the setleds command. One way to guarantee that numlock will be turned on after bootup for the TTYs is to run setleds via rc.local (a script run after every runlevel change; which in particular runs after booting up). To do so add something similar to the following in the file /etc/rc.local:
# Turn Numlock on for the TTYs:
for tty in /dev/tty[1-6]; do
/usr/bin/setleds -D +num < $tty
done