Two hours. Ten candidates. Three moderators.

Simple math says not every -- and perhaps no -- candidate in Thursday's prime-time, top-tier presidential debate is going to get as much time as he would like to make his case to voters.

Some of the 10 candidates' speaking times may be so minuscule that it'll be as if they weren't even there at all, said Alan Schroeder, debate expert and journalism professor at Northeastern University.

We did a little debate arithmetic with Schroeder to give you our best-guesstimates of how long the candidates will have to speak. Have your own debate math? The comment section awaits.

Establish an average based on historical precedent

Which was kind of hard to do. There really isn't a historical precedent for such a crowded debate stage.

Schroeder and Janet Brown, executive director of the nonprofit Commission on Presidential Debates, can remember just a handful of other times when primary debates had nine people -- much less 10. There were 10 Republicans in one of the first debates of the 1996 primary cycle, 10 Democrats in a 2004 primary debate and eight Republicans in a May 2007 debate.

Neither could remember how long the candidates were allowed to speak in those debates. The more typical debate size at this stage of the campaign is about six or seven candidates, and depending on the debate's format, candidates can speak anywhere from 10 to 20 minutes in a 90-minute debate.

The gold standard for allowing ample candidate speaking time comes in a general-election debate, naturally, where there are only two or sometimes three candidates on stage.

In 2012, Brown's commission crafted a 90-minute debate between Republican nominee Mitt Romney and President Obama to have as little interference as possible from the moderator or audience. At the end of one 30-minute segment, they found the moderator had spoken for only two minutes, so the candidates got about 42 minutes of speaking time.

So if history is any guide, we're working with anywhere from 10 to 40 minutes of speaking time for presidential candidates during a debate.

Look at everything else taking air time Thursday

What we know: The debate will be 120 minutes with three moderators.

Assuming the moderators take turns, if they tie America's debate record for quickest moderators ever, they will take up two minutes every 30 minutes. So 1 moderator times 2 minutes times 4 30-minute periods = 8 minutes of the moderators talking. And that's being very generous.

There will almost definitely be some kind of commercial break, likely every 30 minutes. The average commercial break is two or three minutes. This is a big event, so we'll go with the higher average. So 3 minutes times 3 commercial breaks = 9 minutes of commercials.

And it's likely there will be a produced segment or two introducing candidates to voters. We'll reserve a conservative 2 minutes for that.

So 120 minus 8 minus 9 minus 2  = a generous estimate of 101 minutes for the candidates.

Divide candidates into two groups

If life were fair, the candidates would get an equal amount of the remainder of that time, or 101 divided 10 = about 10 minutes each. Remember, that's on the lower end of our historical precedent.

But life isn't fair, and past debates suggest that the moderators will focus their questions and follow-up questions on the top three or four contenders. According to the polls, that's Donald Trump, Jeb Bush and Scott Walker.

Schroeder says we can assume those candidates will get between 10 and 12 minutes of talking time each.

Everyone else? Our best guesstimate is 7-9 minutes each, with those on the edges of the stage getting only about five or six minutes.

Remember that not everyone watches the debate in real time

If all registered voters were required to sit down and watch the debate (9 p.m. Eastern time Thursday on Fox), our job would be done.

But a candidate arguably wins the debate if he or she wins the news cycle. And that means winning the YouTube/cable clip wars the next day.

But being in your own YouTube clip or story isn't always best: Historically, if you have your own headlines, it's because you made a gaffe. (See: 2012, Perry, Rick, "oops")

Media usually covers a successful back and forth between two candidates, so if you somehow managed to break out of the crowd of 10 (and Trump! We haven't even calculated Trump, because he's incalculable!) to win the news cycle, you can expect to split a 30-second clip with someone else. So, 15 seconds.

Factor in the kiddie table debate

There's another forum we haven't even mentioned yet: The seven candidates left out of the top 10, based on the averages of the five most recent polls, will take part in a forum a few hours ahead of time on Thursday.

As we've written extensively at The Fix, the margins of error for these polls are so small that the difference between 9th and 10th place is statistically insignificant. (Brown says some people in the debate community have endorsed picking straws and dividing the candidates into groups of 3 or 4 to debate over a few nights. That's how little these polls tell us.)

We will factor in the earlier debate into our math because, as Schroeder says, it will likely bleed into coverage of Thursday. So minus a few paragraphs or something.

Bottom line

Proving my points above, you scrolled down here without reading everything, didn't you?

Anyways, the bottom line is this: Candidates will have from five to 12 minutes each to make their case on Thursday. To make their case to voters who weren't paying attention Thursday but want to follow up with the debate Friday: About 15 seconds.

Hours and hours of preparation could come down to 15 seconds on Thursday night. This is our political reality.

[Correction: Schroeder is a journalism professor at Northeastern University]