Juha Tuomi/dpa - Math student
Berlin Start-Up: Math42
When brothers Maxim and Raphael Nitsche were 15 and 14 year-old math tutors, they received the same questions over and over. So they created an interactive iPhone app that guides students through complex problems. Now at 19 and 18 years old, their “Math42” app has at times been the most downloaded educational app in Germany and the U.S.