Calculating ERA When a Pitcher Records No Outs: An Explanation

Question
How do u calculate an era when a pitcher faced 6 batters & didn't get an out? You can't figure it out can u? U can't divide by zero? I know how to calculate it if he pitches other innings, but it turned out to be his only appearance of the year.
He faced 6 batters & gave up 6 runs & did not get an out.

Thanx,
PB

Answer
Patrick,

You are right.  You can't calculate an ERA when the pitcher doesn't retire any batters!

Basically, the ERA is infinite.  The record books list it that way when a pitcher allows runs but doesn't retire anyone.

So just show it as infinite.  The symbol is an 8 on its side.

Brian