Reader Gordon Whitney finds the right fifth of his keyboard strangely unresponsive. He writes:
I don’t know why, but a couple of weeks ago the number pad on my Mac’s keyboard stopped working. The Plus and Minus keys seem to work okay but none of the numbers or the Enter key. I’ve tried restarting and looking in the Keyboard and Mouse system preference but nothing fixes it. What’s wrong?
Odds are that you’ve managed to enable an accessibility feature called Mouse Keys. This feature lets you use the number pad keys to move the Mac’s cursor around the screen (8 is up, 2 is down, etc). Although you can switch it on within the Mouse & Trackpad tab inside the Universal Access system preference, it can also be enabled when you press the Option key five times in a row. It’s likely you did that and didn’t notice the little “chitter” sound that indicates Mouse Keys has been switched on
Just bang that Option key another five times and you should hear the descending chitter sound that indicates Mouse Keys is now off and your number pad is ready to use again.