Answer: 2 yuan.
2. Suppose there is a pond with infinite water. At present, there are two empty kettles with a capacity of 5 liters and 6 liters respectively. The problem is how to get 3 liters of water from the pond with only these two kettles.
Answer: Fill it with a 5-liter pot and pour it into a 6-liter pot.
Pour the 5-liter pot into the 6-liter pot until the 6-liter pot is full. At this point, there are 4 liters of water left in the 5 liter pot.
Pour all the water out of the 6-liter pot, and pour the remaining 4 liters of water from the 5-liter pot into the 6-liter pot. At this time, there are only 4 liters of water in the 6-liter pot.
Fill the 5-liter pot again and pour into the 6-liter pot until the 6-liter pot is full. At this time, there are only 3 liters of water left in the 5-liter pot.
3. A farmer took three rabbits to the market to sell. Each rabbit weighs about three or four kilograms, but the farmer's scale can only weigh more than five kilograms. He asked him what he called it.
Answer: weigh three first, then take one, and then calculate the difference after weighing.
A monkey picked 100 bananas in the forest and piled them up. The monkey's home is 50 meters away from the banana pile, and the monkey intends to carry the bananas home.
You can take up to 50 sticks at a time, but monkeys are greedy. He eats a banana every meter. Ask the monkey how many sticks he can take home at most.
Bananas?
Answer: 25.
Recite 50 songs to 25 meters first. At this time, I ate 25 pieces and left 25 pieces. Put them down. Go back and recite the remaining 50. At 25 meters, I ate 25 more, and there are 25 more. Then pick up 25 roots on the ground, 50 of them, and continue to walk home. A ***25 meters, you have to eat 25, and there are 25 left to get home.
One day, a young man came to boss Wang's shop to buy a gift. The cost of this gift is 18 yuan, and the price is 2 1 yuan. As a result, the young man took out 100 and bought this gift.
Boss Wang didn't have any change at that time, so he changed 100 yuan from the neighborhood and gave it to the young man 79 yuan. But later, the neighborhood found that this 100 yuan was counterfeit, and Boss Wang had no choice but to return this 100 yuan to the neighborhood. The question now is: How much did Boss Wang lose in this transaction?
Answer: 97 yuan.
6. The sum of four digits and its digits is 1972. Find this four-digit number
Answer: Because it is a four-digit number and the sum is 1972, the thousands of this four-digit number must be 1, because it cannot be 0 or greater than 1.
So this number is 1xxx.
The remaining three numbers are 1972, 9+7+2= 18, 18+0 = 19. So the number in the hundredth place can only be 9, because it is impossible to get 19xx from other numbers.
Then let one digit be x, ten digits be y, and both x and y are integers from 0 to 9.
Then there are:1900+10y+x+y+10 =1972, and 1 1y+2x=62.
X=(62- 1 1y)/2 If you put the number from 0 to 9 in the position of Y, you will find that it can only be y=4 and x=9.
So it is 1949.