<p>Yes.  The test is that in order to be a valid proof of work, the hash found must be numerically less than or equal to the target.  That is certainly true of the hash found by Miner A in your example.</p>

CC BY-SA 3.0
2014-08-14T08:28:54.193Z
Thanks, Still I am not clear.

I referred http://blockexplorer.com/ some completed blocks,and found "Hash Value" has same number of Previous zeros as target has. I mean if Target has 4 previous zero(0x000043AbC..),then found hash has same number of zero(0x000024C...).

Why all the Found hash same number of zeros? It may also generate more than 4 zeros and satisfy less than target.
Tushar
CC BY-SA 3.0
2014-08-14T15:35:57.690Z
@tushar: It certainly could have 4 more zeros, but this will only happen 1/65536 of the time, so it's not surprising we rarely see it.
Nate Eldredge
CC BY-SA 3.0
2014-08-13T15:54:33.740Z
2014-08-13T15:54:33.740Z
Nate Eldredge
<p>Suppose below is target difficulty:</p>

<pre><code>0x0000CDEF0A000000000000000000000000000000000000000000000000000000
</code></pre>

<p>So result value must lower than target to select block.</p>

<p>So, If Miner 'A' found:</p>

<pre><code>0x000000000000000000000000076898778ABEFDC34798734590349843BDCAE854
</code></pre>

<p>Will miner 'A' can satisfy target difficulty or not?</p>

<p>And if not then please tell me the reason.</p>

<p>Thanks</p>

<block><difficulty>
What is the algorithm of block selection using Target Difficulty?
Tushar
# What is the algorithm of block selection using Target Difficulty?

(Asked by: username_0 on 2014-08-13)

Suppose below is target difficulty:
0x0000CDEF0A000000000000000000000000000000000000000000000000000000

So result value must lower than target to select block.
So, If Miner 'A' found:
0x000000000000000000000000076898778ABEFDC34798734590349843BDCAE854

Will miner 'A' can satisfy target difficulty or not?
And if not then please tell me the reason.
Thanks

**Tags:** block, difficulty


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## 1 answers

### Answer by username_1 on 2014-08-13. Score: 1

Yes. The test is that in order to be a valid proof of work, the hash found must be numerically less than or equal to the target. That is certainly true of the hash found by Miner A in your example.

> **Comments:**
> **username_0**: Thanks, Still I am not clear.  I referred http://blockexplorer.com/ some completed blocks,and found "Hash Value" has same number of Previous zeros as target has. I mean if Target has 4 previous zero(0x000043AbC..),then found hash has same number of zero(0x000024C...).  Why all the Found hash same number of zeros? It may also generate more than 4 zeros and satisfy less than target.  
> **username_1**: @tushar: It certainly could have 4 more zeros, but this will only happen 1/65536 of the time, so it's not surprising we rarely see it.  

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