I came across this and couldn't not share with you: The Bitcoin Puzzle. In 2015, someone created the puzzle by creating 160 wallets and sending Bitcoin to each of them.

Why?

Just for fun - and to show how secure bitcoin private keys are. Your seed phrase results in a 256-bit private key (256 0s and 1s). Guessing a particular private key is like winning PowerBall 9 times in a row.

If Bitcoin private keys are so secure, how do I solve the puzzle?

Each private key was created with leading zeros, which means you will only have to guess the remaining bits. The first puzzle was too easy: just one bit. The key was 0000000000000000000000000000000000000000000000000000000000000001.

Each private key has one more bit and the first 65 have already been solved.

What is the lowest hanging fruit?

Puzzle #66 offers 6.6 BTC and has 66 bits to guess:

source: privatekeys.pw

Here's the address: 13zb1hQbWVsc2S7ZTZnP2G4undNNpdh5so

How - and how likely is a solution?

The most efficient way is to use a GPU. An RTX3080 can solve 1.6 billion keys per second, using CuBitCrack on GitHub. It's an open source project written in Python*. You'll find a tutorial there.

CuBitCrack crunching numbers

36,893,488,147,419,103,231 possible keys divided by 1,600,000,000 keys/s gives 2.3*10¹⁰ seconds - or 731 years to guess them all. To guess 1% of all keys, it would take 2,668 days and consume about 19,215 kWh of electricity. With 10 cents per kWh this would cost you about $1,922.

6.6 BTC are worth $188k right now. That means you'd have a chance of 1% to win it for $1,922 which is slightly more than 1% of the price.

Conclusion

It's a fun way to learn about bitcoin private keys and open source software written in Python. The odds are better than playing the lottery and the expectation value is better too! On the plus side: your computer can heat your office when it's cold, so the energy isn't wasted!

/edit: Isn't it ironic - my first really successful post - one day before they pull the plug on Moons.

^\I've created a python script that uses random keys in a certain range with every start. Feel free to ask in the comments if you're interested. I didn't want to scare off readers by posting code.)