It’s a common challenge for almost every startup: how much and how fast to grow. But Vijay Shekhar Sharma, founder of the Indian mobile payments and commerce platform Paytm, knows that he wants to take his company to $100 billion and replicate its model in other emerging markets. Harvard Business School professor Sunil Gupta discusses his case “Paytm: Building a Payments Network” — how reaching Sharma’s lofty goal won’t be about technology and finding new solutions, but rather all about finding new use cases for existing solutions.