Principles of mining
 For example, I told the three friends that the thought of a number from 1 to 100. I recorded this number on the worksheet that was hidden in the envelope. My friends don't even need to guess the exact number — just the first to call a number that is less than or equal to the number in the envelope. The number of attempts is not limited. Suppose I have in mind 19. If a friend And say "21" he will lose because 21 is bigger than 19. If each says "16" and each is "12", both answers can theoretically be counted, because and 16, and 12 is less than 19. Friend B does not receive any additional benefits, although his response was closer to the target number wins the one who offers your first option. What happens if friends B and C are answered at the same time? In the bitcoin network simultaneous responses occur regularly, but the award can only get one. In this situation, to decide which of the miners is worthy of, should the entire network. The decision is taken by simple majority of votes — 51%. Typically, the award goes to the miner who has accomplished more useful work, i.e. was verified by the most transactions