First, I'm sorry if I'm asking a stupid question. I'm just trying to understand bitcoin. I'm reading the Ethereum white paper, and I couldn't understand this sentence about proof of work:
At the current target of ~2^187, the network must make an average of ~2^69 tries before a valid block is found
My question: how the 2^69 number of tries is computed?
My question: why 2^69 instead of 2^70 or 2^169?