A secret and simple way to keep chickens and rabbits in the same cage

The simple solution to the problem of chickens and rabbits in the same cage is as follows:

1, hypothesis method

Assuming that they are all chickens, the number of rabbits is: (total number of heads x2- total number of feet) ÷2.

Assuming that they are all rabbits, the number of chickens is: (total number of heads x4- total number of feet) ÷2.

Total number-number of chickens = number of rabbits

Basic principle: If the total number of heads x2 = the total number of feet, it means all chickens, if; The total number of feet indicates that there are chickens, and there are only 1 chicken for every two extra feet.

2. Formula method

Total number of feet ÷2- total number of heads = number of rabbits

Total-number of rabbits = number of chickens

Basic principle: It turns out that the total amount of head is the total amount of chicken head and rabbit head, and the total amount of feet is also the total amount of chicken feet and rabbit feet. The total number of feet ÷2 is calculated as all chickens, if quotient = total number of chickens, it means all chickens, if quotient >; The total number of heads indicates that there are rabbits among them.

Every 1 elephant is 1 elephant. Because 1 has four feet, the rabbit in front of 2 1 has two heads, which means 1 head is more, so the difference between the total number of feet and the total number of heads is the number of elephants.

3. Exclusion method

(total number of feet-total number of heads x2)÷2= number of rabbits; Total-number of rabbits = number of chickens

Basic principle: First, let each chicken and rabbit lift their feet separately. At this time, the chicken has no remaining feet, and the remaining feet are strip-shaped after removing the chicken. Lift two feet in front, and now there are two feet left in each. So the difference between the total number of feet and the total number of heads, x2, 2, is the number of rabbits.