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 = ( "4cdd838fbb gives 103 0xfcoins to" + "807b9f7190" + nonce)

nonce = "132f4c5f0f"
sha1("string1"+"string2"+nonce) -> Results in sha1 hash 000000593a640078a309840d69b4e2064d09ae20 so 132f4c5f0f would be the solution if we were looking for 6 leading zeroes