Level 38

You don't need a Bitcoin miner to proof that you can do some work.
Seal the block by finding a nonce that (combined with the data) will return a sha1 hash with 7 leading zeroes

sha1 = ( "504ac2a0bf gives 200 0xfcoins to" + "856926fa5a" + nonce)

nonce = "dnt28wclnx"
sha1("string1"+"string2"+nonce) -> Results in sha1 hash 000000140e9731bbf369d8cbc4f7919961020793 so dnt28wclnx would be a solution if we were looking for 6 leading zeroes