The hottest recent iPhone app debut isn’t about photo sharing or social networking: PhotoMath, which just launched last week, uses an iPhone’s camera to read and solve math problems in real time. It led Apple’s iOS store in overall US downloads last Wednesday and remained there into early this week. (It is currently No. 2 in the US store).

More than six million people have downloaded the app since its launch, according to Microblink, the Croatia-based developer of PhotoMath. It has become the no. 1 app in 82 countries, according to app store-tracker App Annie (registration required).

“We’ve been blown away with the response from users,” Izet Zdralovic, co-founder of Microblink, tells Quartz. “With PhotoMath, we feel we’ve connected two unusual things—real-time data with optical character recognition (OCR) and math—and that has never been done before.”

As we noted at the time of the app’s launch, the technology behind the app works like this: A user points a mobile camera at a mathematical equation. The app recognizes the problem and does the math. Within one to two seconds, the app sends back a solution to the equation—along with a step-by-step process on how to solve the problem. A valuable aid for a student eager to understand the process or check her work—or an easy shortcut for the crafty cheater ordered by a teacher to “show your work.”

Is it cheating?

As soon as PhotoMath launched, it was criticized for promoting cheating.

A glance at the App Store reviews shows that’s not unfounded. Here’s one, from a user that goes by Kyle M. Horton: “No one is going to use this to check their work. I need to pass Algebra 2 with an A for college and I am horrible at math. This app just made things a whole lot easier.”

“I am 15 and this app may be handy to allow me [to] understand the problem I am having trouble with. Others will use it to simply cheat,” said another (purportedly more conscientious) user, Ninjump21.

In response, the company wrote a blog post Thursday addressing the concerns—essentially saying that students looking to cheat would cheat anyway, with or without PhotoMath. They said they saw PhotoMath as a sort of 21st-century calculator: “We’re sure that the same questions were raised when calculators entered classrooms,” they wrote. “With PhotoMath, our goal is to make a much more useful calculator.”

PhotoMath’s technology extracts data from the user’s scan of a mathematical equation, and then processes it through a built-in repository of mathematical algorithms that do indeed act like an advanced calculator.

The difference between PhotoMath and some competing apps that send the math problem to a server and get back a solution, Zdralovic explains, is that those processes require an internet connection, whereas PhotoMath does not. This makes the app more viable for users in the developing world, he says, allowing them to find solutions to math problems even if they’re offline.

Next steps for growth

Zdralovic says that Microblink is funding PhotoMath itself without outside investors. The company—which has 12 employees and is based in the capital Zagreb with a second office in London—draws most of its revenue from licensing proprietary software development kits (SDKs) to large firms inside and outside Europe. Zdralovic would not say what the company is currently worth or what PhotoMath’s revenue model will be going forward. He did say, however, that there are “three or four major US publishing companies who’ve approached us about scaling up PhotoMath.” But he declined to name them or expound on the details of such an agreement, saying he was bound by a non-disclosure agreement.

PhotoMath has far surpassed its initial expectation of just 100,000 downloads, and has ambitions to expand its reach in the coming months, says Zdralovic. The next stages will focus on adapting the app to a number of foreign languages and to handle more complex mathematical functions. PhotoMath currently handles only work done at the US 8th and 9th grade level, he said, including the equations students would encounter in Algebra 1 or Algebra 2.

The main focus for now, however, is expanding the app to Android phones. PhotoMath’s developers in Croatia have set a target date of January 2015 for that release.