Meet high school student Felix Zhang, who this year became the only person in the world to earn a perfect score on the AP Calculus exam. ABC News’ Lionel Moise has the teen’s winning formula. Original source (ABC/Youtube)

रिज़वान और शादाब ख़ान के दम पर पाकिस्तान ने सुपर 4 में बनाई जगह, मैच का सटीक विश्लेषण वसीम जाफ़र के साथ #AsiaCup #ShadabKhan #MohammadRizwan #Pakistan #INDvPAK #wasimjaffer Subscribe to ESPNcricinfo: http://bit.ly/1jnGh6S Get our apps: Android: http://bit.ly/2vFVfzX iOS: http://apple.co/2vGj8rg Website: http://www.espncricinfo.com/ You can also find us at: https://www.facebook.com/Cricinfo Tweets by ESPNcricinfo https://www.instagram.com/espncricinfo/ source

U.S. and NATO officials expect that Russian President Putin will use the vote to justify annexing more Ukrainian land and then threaten to defend the territory with nuclear weapons. NBC News’ Richard Engel has new details on the conflict and Russian men trying to escape the country to avoid being drafted. » Subscribe to NBC News: http://nbcnews.to/SubscribeToNBC » Watch more …