user69019: What is the computational effort to mine a block successfully given the number of leading zeros in a resulting hash?

user63872: The difficulty does not specify a certain amount of computational effort that needs to be expended. In other words, the difficulty is not set to '1000 effort', and miners slowly progress from 0 to 1000, with the first one to expend 1000 effort winning the next block. 
Instead, you need to think of it like a lottery. You can expend effort to make a guess, and if your guess is correct, you win the next block! The higher the difficulty, the lower the odds of any one guess generating a valid block. 

69019: <p>What is the computational effort to mine a block successfully given the number of leading zeros in a resulting hash?</p>
 63872: <p>The difficulty does not specify a <em>certain amount</em> of computational effort that needs to be expended. In other words, the difficulty is <strong>not</strong> set to '1000 effort', and miners slowly progress from 0 to 1000, with the first one to expend 1000 effort winning the next block. </p>

<p>Instead, you need to think of it like a lottery. You can expend effort to make a guess, and if your guess is correct, you win the next block! The higher the difficulty, the lower the odds of any one guess generating a valid block. </p>
