Two individual Bitcoin miners with modest hashrate hit a jackpot of 6.25 BTC each (around $275,000 at current prices) after successfully adding new blocks to the Bitcoin network—all in the span of two days.

Both lucky miners had their computing power connected to Solo CK, a mining pool offering anonymous solo Bitcoin mining.

Dr. Con Kolivas, a software engineer who created the Bitcoin mining software CGMiner and also operates Solo CK, took to Twitter to share the news of the first miner to mine block #718124 on Tuesday with a mere 126 terahashes per second (TH/s) hashrate.


When asked what are the chances of adding a valid block to the Bitcoin network with such a low hashrate, Dr. Kolivas said it depends on how long they have been mining.

To his estimates, there’s a 1 in 10,000 chance of finding a block per day with that hashrate, or one block on average every 27 years.

120 TH/s hashrate equals 0.00012 EH/s, or about 0.000068% of the Bitcoin network’s total computing power, which currently stands at 176.4 EH/s, according to


What’s even more remarkable is that this event happened twice in just three days.


On Thursday, another worker from Solo CK was able to solve block #718379 with a capacity of only 116 TH/s, even less than that of the first miner.

According to Dr. Kolivas, the second miner joined Solo CK just two days ago, “presumably in response to the other lucky block solver, so they've been astronomically lucky in solving a block solo in that time.”

He added that, as far as the second lucky worker was concerned, the chances of finding a new block at the pool by that time were about 1 in 6,000 since the time they had started mining.

Why is solving Bitcoin blocks so hard?

Bitcoin mining is the process of adding and verifying blocks of transactions to Bitcoin’s public blockchain. To add new blocks, miners compete with each other by solving complex cryptographic puzzles to get newly-minted Bitcoin as a reward—currently 6.25 BTC per block.

In the early days of Bitcoin, when the mining difficulty, a measure of how hard it is to mine new coins, was low, it was possible to mine new coins using simple CPU chips found in home computers.

This is exactly what Satoshi Nakamoto, the pseudonymous inventor of Bitcoin, did on January 3, 2009, when he mined the first batch of 50 Bitcoin.

As mining became more difficult, and with the mechanism of halving Bitcoin rewards, CPUs became less and less efficient, as did solo mining.


As time went on, CPUs were replaced with more advanced graphic cards (GPUs), which soon became outdated too, leaving the lane to application-specific integrated circuit (ASIC) chips.

Today, when both Bitcoin hashrate and mining difficulty are at historical heights due to the industrial scale of mining, it's becoming more and more difficult to make money from the venture as an individual miner.

Still, recent events prove that it’s not impossible.

And as Dr. Kolivas put it, “if enough solo miners do it for long enough, then statistically someone is going to find a block.”

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