About a half-hour into a conference call with reporters Friday afternoon, senior Internal Revenue Service official Lois Lerner said something she will regret.

“I’m not good at math,” she confessed as she tried to summon a statistic.

Lerner clarified that she is a lawyer and not an accountant (a fair defense) but the remark instantly blew up on Twitter — an IRS official being bad at math — and wound up punctuating what was a torturous response to the IRS’ admission that it inappropriately targeted tea party groups.

See: IRS targeted tea party, patriot groups for scrutiny

A skeptical press corps peppered Lerner with questions, many of which she and her staff were unable or unwilling to answer.

A sampling:

1. IRS officials claimed that there was no political bias behind the targeting of these conservative groups, but they failed to produce any examples of similar targeting of groups with non-conservative-sounding names. Initially, they suggested that other non-conservative-sounding names might have been targeted. By the end of the call, though, Lerner acknowledged: “I only said that because I never like to say ‘absolutely not.’ I don’t have any information on that.”

2. Lerner wouldn’t say whether anyone is being disciplined, then appeared to say there was no disciplinary action, then went back to saying she wouldn’t comment. Federal personnel rules appear to prohibit Lerner from discussing discipline, so she has some justification for not commenting. But that justification was never explained, and instead she was pressed repeatedly on why she wouldn’t discuss discipline.

3. Lerner said she disclosed the information because someone asked her about it Friday morning — indicating that she had no plans to release the information publicly, despite the confirmed wrongdoing.

4. When asked how they found out about the wrongdoing, Lerner said the investigation stemmed from media reports about conservative groups claiming that they were targeted, not from any internal review.

5. Lerner and her staff tried to get off the phone call after less than half an hour of questioning, but Columbia Journalism Review reporter  David Cay Johnston informed them that they had better stay and answer everyone’s questions. They stayed on the call for another 20 minutes. By the end, they said Lerner had to get to some appointments and cited the “repetitive” line of questioning. Johnston informed them that it was because they weren’t answering the questions.