Nearly 25% of queries fielded by the Wolfram Alpha answer-engine come from Apple’s voice-powered assistant Siri, according to the New York Times. Wolfram Alpha is an online service that gives fact-based answers to queries directly from its database rather than by searching through web pages that might contain the answer. The service was launched in 2009 by British scientist Stephen Wolfram. Apple partnered with the answer-engine for the company’s voice assistant that launched with the iPhone 4S and since then, the Wolfram Alpha staff has grown to 200 employees. A new enhanced version of the service called called Wolfram Alpha Pro is set to launch on Wednesday. Dr. Wolfram called the version “the next step of what can be done with this approach,” and access to the premium version will cost $4.99 per month, or $2.99 for students.