The first concern in answering “how many Bitcoins are there left” directly points to Bitcoin mining. Bitcoin works on one fundamental principle, and that is Bitcoin mining, a process for the creation of new Bitcoins through solving mathematical puzzles. Miners compete with each other for solving mathematical puzzles to verify transactions before adding them to the Bitcoin blockchain. cryptocurrency usbased bit digital usstreetjournal After early "proof-of-concept" transactions, the first major users of bitcoin were black markets, such as the dark web Silk Road. During its 30 months of existence, beginning in February 2011, Silk Road exclusively accepted bitcoins as payment, transacting ₿9.9 million, worth about $214 million.: 222 That means about 18.9 million coins out of the maximum supply of 21 million are now on the open market. But mining the final 10% isn't expected to happen until February 2140, based on network estimates and bitcoin halving schedules, CoinDesk reported.