Fortune Telling Collection - Free divination - Nine coin problems

Nine coin problems

The concept of two hands, I think, refers to whether the two sides have the same mass when the number of coins held by the left and right hands is the same, so I give the solution for three times as follows.

The first time, left hand: 3, right hand: 3.

This is divided into two situations.

1. If both hands are equally heavy, the six coins on the left and right hand are standard coins. Then one of the remaining three coins is not a standard coin. Let these three coins become ABC ... for the second time, both hands are AB, and if they weigh the same, C is a special coin. If not, the third time: the left and right hands are AC, if they are the same weight, B is a special coin, if they are not the same weight, A is a special coin. (This situation is relatively simple)

2. If the weights of the two hands are different, the coin on the heavy side is ABC, the coin on the light side is DEF, and the remaining three coins must be standard coins, that is, XXX: the second time: the left and right hands take ABC and XXX respectively. Here, there are two situations.

(1)ABC is heavy, so one of ABC is special currency, and the special currency is biased. At this time, you can choose two pieces (such as A and B) to compare their weights. The heavier piece is a special coin. If the quality is the same, the third piece is a special coin.

(2) With the same weight, one of the DEF coins is a special coin, and the special coin is lighter. At this time, you can choose two pieces (such as A and B) to compare their weights. The lighter piece is a special coin. If the quality is the same, the third piece is a special coin.

Simply put-first take out a coin, then take four coins in one hand, see which one is heavy, and put down the other five coins; Take two coins in each hand, which side is heavy, and then take off two coins in one hand, and the coin in the other hand is light, which is a special coin.