Comment 38 for bug 201887

There is also a simpler way to fix the numlock issue:

1. make sure, you have xmodmaps installed (this should be by default)
2. create the file ~/.xmodmaps
3. paste the following into the file:

keycode 79 = 7
keycode 80 = 8
keycode 81 = 9
keycode 83 = 4
keycode 84 = 5
keycode 85 = 6
keycode 87 = 1
keycode 88 = 2
keycode 89 = 3
keycode 90 = 0
keycode 91 = period
keycode 82 = minus
keycode 86 = plus
keycode 157 = equal
keycode 77 = F20

the last line remaps the clear (=numlock) key to behave as F20 instead.