Primecoin is a cryptocurrency based on finding prime numbers. Identifying prime numbers plays a central role in cryptography. Primecoin's unique Proof-of-Work (PoW) consensus mechanism is able to increase transaction speeds and improve energy efficiency.
The network searches for special prime number chains known as Cunningham chains and bi-twin chains, which are of interest in mathematical research.

Unobtanium is a Proof-of-Work (PoW) cryptocurrency that uses the SHA-256 hashing algorithm. It was designed to serve as a commodity and store of wealth that would be less vulnerable to price fluctuations. The coin's supply is limited to counter inflation, and UNO coins were distributed in a manner that would discourage centralization. UNO can be merge-mined with Bitcoin.

GAS is the token that is used to pay for transaction fees on the NEO network. The NEO platform uses two different tokens; GAS are used to fuel the network and give holders the right to use the NEO blockchain. Similar to Ether on the Ethereum network. Although it's possible to buy GAS on some exchanges, NEO token holders automatically generate GAS as the blockchain increases in size. 8 GAS are distributed for every 100 million NEO in circulation.

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