Tactfully point out the error and convince him to let you onto his computer to correct it. When you're done, right click on the desktop, enter graphics properties, and put his monitor in landscape mode. If he can't get his numbers right, he probably can't fix the monitor.
I'm facing a long night of a party with my wife's relatives. On the positive side, it will be on a party boat. On the negative side, no one will be speaking English, and I know I will end up sitting alone on the side with no one to talk to. What can I do to have a better time?