We don’t know the exact number of Oz and McCormick votes right now. Here’s why.

Here’s a trick question: How many votes have been counted for Mehmet Oz and David McCormick?

The top two candidates for Pennsylvania’s Republican Senate primary are fewer than 1,000 votes apart, prompting an automatic recount — and that recount is already underway.

But we don’t actually know exactly how many votes the two candidates received during the first count of the ballots.

It’s not that you can’t find precise numbers. As of 9:30 a.m. Tuesday, for example, the Pennsylvania Department of State was reporting 419,510 votes for Oz and 418,588 votes for McCormick statewide. The Associated Press, meanwhile, was reporting 419,631 votes for Oz and 418,706 for McCormick.

It’s just that both sources are probably slightly wrong. They’re pretty close to each other, and to the right number. We just don’t know what that right number is.

The numbers aren’t final yet, and that’s not unusual. It’s why certification isn’t for another week. It’s also not unusual that different sources have slightly different numbers, because reporting can lag and sometimes have typos and other mistakes. We just normally don’t notice because the races have usually long been called by this point and we’re not paying attention to the final numbers. This time, the numbers are so close we’re in a recount, and a lot of people are watching closely.

And this election, there’s an additional layer of muddiness: Some counties are including undated mail ballots in their main results, while others aren’t. So the statewide numbers, even when accurately summarizing what counties are reporting, are an inconsistent patchwork of numbers.

Here are some reasons why we don’t know how many Oz and McCormick votes were tallied in the first count of votes:

The first count of ballots isn’t complete yet — there are still a handful of votes left to count in a few pockets around the state.

While the vast majority of votes were counted very quickly — within hours of polls closing — some always take more time. Some mail ballots, for example, are submitted with defects that require elections officials to decide whether to count or reject them. Similarly, provisional ballots — last-chance ballots that voters use at polling places when there’s some question about their eligibility to vote — require counties to research the voters and whether to count their votes.

Philadelphia elections officials on Friday voted on approving and rejecting the very last votes: a handful of ballots involved in a South Philly mail ballot delivery effort and provisional ballots that had been challenged by the McCormick and Oz campaigns.

There’s a two-day waiting period to allow for campaigns to appeal those decisions to county court, so those votes won’t get counted until after 5 p.m. Tuesday. (They’ll then be immediately rescanned as part of the recount.) Until then, Philadelphia’s initial vote count is incomplete.

Similarly, Allegheny County had 30 challenged provisional ballots. Of those ballots, county officials decided Friday to count 26 and reject four. The county plans to scan those last ballots Wednesday, after the two-day waiting period.

The question of whether to count undated mail ballots — those that were received on time but without the voter writing a date on the envelope, as required by law — has shaken the race.

As the Oz and McCormick campaigns battle it out in the courts, and the Lehigh County case is put to the U.S. Supreme Court, counties are left having to report their numbers one way or another.

And they’re making different decisions.

Philadelphia, for example, includes undated mail ballot results on its website and what it reports to the state. The Department of State and AP reflect those numbers.

Delaware County doesn’t include undated ballots, and the state and AP show those numbers.

Centre County included undated mail ballots on its website, though it did not mean to — and the AP used those numbers, while the state showed the number excluding undated ballots.

» READ MORE: What to know about the Pa. Republican Senate primary recount

Because some counties are reporting undated mail ballot results and others are not, statewide aggregations of those numbers are inherently wrong. In theory, there can be two different right numbers: the exact number of votes counted including undated mail ballots or the exact number excluding those ballots. But instead of giving one or the other, the statewide numbers are a mix of both, meaning that number isn’t exactly right.

It’s only a temporary issue, because the courts are actively looking at whether to count undated mail ballots. But for now, it means we don’t have an exact count.

A federal appeals court said days after the election that undated Lehigh County mail ballots should be counted from November’s election. While that ruling wasn’t about this election, the Department of State, some counties, and the McCormick campaign believe its underlying logic still applies. Because the handwritten date is a technicality counties don’t use to determine the legitimacy of a vote, the court said, rejecting ballots over it is a violation of federal civil rights law.

The McCormick and Oz campaigns have scrambled to respond to that ruling, and on Tuesday argued before the state’s Commonwealth Court about whether to accept or throw out undated ballots in this election.

That’s left counties in a bind, and the Pennsylvania Department of State has advised them to count undated ballots — but to keep both the results and physical ballots separate from the rest of the vote. That practice of “segregating” ballots is common in election administration as a way to continue with the vote count while allowing litigation to play out in the courts; whatever the ultimate legal conclusion, the votes can be easily added or removed from the totals.

Counties run elections, with the state overseeing but not directly administering them.

That means the results come directly from each individual county, which then shares those results with the state. The Pennsylvania Department of State provides unofficial running tallies based on those results counties send to the state database. That system is usually behind the real-time vote counts, so on election night, county websites are often ahead of the state’s.

The lag continues now. When a county releases a new batch of results, it can take a bit for those numbers to show up on the state site. Last Wednesday, the Department of State moved from the normal file-uploading process to a manual one: Counties now submit PDFs to the state, and a worker there manually updates the website.

» READ MORE: McCormick and Oz are fighting over tiny batches of votes in county after county

There’s also the possibility for error in that process, or for counties to simply forget to send updated results to the state.

“We are only as good as the data that is being uploaded,” department spokesperson Grace Griffaton said Friday. “The information we can provide Pennsylvanians is the information being provided by the counties.”

The other major source of election results is vote aggregators such as the Associated Press, which on election night has people across the state reporting the results as quickly as counties release them. That’s why the AP’s numbers are usually slightly higher than the state’s. There can also be small mistakes made in that process, too, and the AP occasionally finds and corrects those errors when it validates its data; that’s happened in this election.

Small mistakes also sometimes occur at the county level.

Over the weekend, Philadelphia updated its numbers slightly, dropping Oz’s vote by one and McCormick’s vote by two. A spokesperson for city elections officials said that was because workers during the cleanup process found that on one machine they had forgotten to clear the testing data. They re-scanned the real votes to correct the number.

For now, we know the vote counts are extremely close. We’ll have real answers soon enough as to just how close: Counties will finish their initial vote counts and then the recount, and courts will decide what to do with the undated mail ballots.

The state will report the official, final recount numbers June 8. By then, we’ll also know the initial count, so we can see how the recount changed those numbers. We’ll just have to wait a little longer to know what those numbers are.