problem – Is not Bitcoin’s hash goal speculated to be an influence of two?
As Andrew’s reply factors out, the ‘variety of main zeros’ is only a simplification, so I believed I’d give an instance to extra concretely illustrate this:
Block hashes are often represented in hex format, which makes use of the character set [0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f]. However for simplicity, we will simply use a base 10 quantity set [0,1,2,3,4,5,6,7,8,9], the very same ideas apply.
The block hash is the output of a SHA256 operation, so it’s a 256-bit quantity, which is a really massive quantity. This implies the output of the SHA256 operation will likely be a quantity within the vary of 0 to 2^256. Once more although, for simplicity sake we will think about a a lot smaller quantity vary in our instance, so we’ll use the vary 0 to 1,000,000 as an alternative.
Now, lets think about that the hash goal is
≤500, thus any in any other case legitimate block enter that provides an output of
0000500 or much less can be thought of a sound block. Lets additionally think about that the hash goal adjustments to be
≤450 for the subsequent problem interval, making any output of
0000450 or much less a sound block.
Discover that these two targets would “require the identical variety of main zeros”, however a block that hashes to
0000475 would solely be legitimate within the earlier problem interval, and never the later. It is because the hash goal is a particular quantity, the variety of main zeros is just a simplification/tough proxy for this.