<p>Sounds like he calculated 59 days first, using the method you mention. And then for some reason did 59 * 6 * 24 (1 block per ten minutes) to come to 8496.</p>

<p>I agree that it confuses more than it adds.</p>

CC BY-SA 3.0
2016-02-29T21:38:07.813Z
Would you know how 59 days was calculated? By my calculations, at 1 TH/s, it would take 1,152,921 seconds to try every possible value. ie 13 days.
cloudnthings
CC BY-SA 3.0
2016-02-29T12:58:10.213Z
2016-02-29T12:58:10.213Z
Jannes
<p>In <a href="http://chimera.labs.oreilly.com/books/1234000001802/ch08.html#difficulty_bits" rel="nofollow">Mastering Bitcoin in the section on Difficulty Bits</a> Andreas notes: </p>

<blockquote>
  <p><em>This means that a valid block for height 277,316 is one that has a block header hash that is less than the target. In binary that number would have more than the first 60 bits set to zero. With this level of difficulty, a single miner processing 1 trillion hashes per second (1 tera-hash per second or 1 TH/sec) would only find a solution once every 8,496 blocks or once every 59 days, on average.</em></p>
</blockquote>

<p>How was 59 days calculated?</p>

<p>2^60 (1.15 x 10^18) would be the number of possible values to cycle through and 1 TH/s = 1 x 10^12 attempts every second but what am I missing?</p>

CC BY-SA 3.0
2016-03-02T06:52:17.143Z
I also get an expected 13 days, perhaps you should write an email to Andreas or open an issue on [GitHub](https://github.com/bitcoinbook/bitcoinbook).
Murch
<hash><difficulty><mastering-bitcoin>
How was 59 days determined with 1 TH/sec from "Mastering Bitcoin"
cloudnthings
# How was 59 days determined with 1 TH/sec from "Mastering Bitcoin"

(Asked by: username_0 on 2016-02-29)

In [Mastering Bitcoin in the section on Difficulty Bits](http://chimera.labs.oreilly.com/books/1234000001802/ch08.html#difficulty_bits) Andreas notes:

> *This means that a valid block for height 277,316 is one that has a block header hash that is less than the target. In binary that number would have more than the first 60 bits set to zero. With this level of difficulty, a single miner processing 1 trillion hashes per second (1 tera-hash per second or 1 TH/sec) would only find a solution once every 8,496 blocks or once every 59 days, on average.*

How was 59 days calculated?

2^60 (1.15 x 10^18) would be the number of possible values to cycle through and 1 TH/s = 1 x 10^12 attempts every second but what am I missing?

**Tags:** hash, difficulty, mastering-bitcoin

> **Comments:**
> **username_1**: I also get an expected 13 days, perhaps you should write an email to Andreas or open an issue on [GitHub](https://github.com/bitcoinbook/bitcoinbook).  

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## 1 answers

### Answer by username_2 on 2016-02-29. Score: 0

Sounds like he calculated 59 days first, using the method you mention. And then for some reason did 59 \* 6 \* 24 (1 block per ten minutes) to come to 8496.

I agree that it confuses more than it adds.

> **Comments:**
> **username_0**: Would you know how 59 days was calculated? By my calculations, at 1 TH/s, it would take 1,152,921 seconds to try every possible value. ie 13 days.  

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