Snap (NYSE: SNAP) has disclosed, in its S-1 Registration Statement, that the company's flagship Snapchat platform now has 158 million daily active users (DAUs). This DAU base also serves as the basis for how Snap calculates average revenue per user (ARPU), which is slightly different from other social networks, which often calculate ARPU based on monthly active users (MAUs).However, Snap has decided not to directly disclose how many MAUs it has, opting to only detail its DAU levels -- which are already starting to see signs of rapid deceleration in sequential growth.