On many machines, you can set whether or not Number Lock is turned on on boot, in the BIOS settings (accessible when you first power on the machine).

Otherwise, there are a number of ways to enable (or disable) Number Lock in software, depending on your specific needs. The most useful ways are listed here.

If you want Number Lock turned on when Ubuntu starts (not before that on the GRUB menu, and not afterwards when logging in, and not just for specific virtual consoles), then install numlockx and make the initialization script /etc/init.d/rc.local use it to enable Number Lock:

sudo apt-get update

sudo apt-get -y install numlockx

sudo sed -i 's|^exit 0.*$|# Numlock enable

[ -x /usr/bin/numlockx ] && numlockx on



exit 0|' /etc/init.d/rc.local

^{Source: NumLock, by Contributors to the Ubuntu documentation wiki, last line taken verbatim (as this source permits).}