The problem of pouring water in primary school mathematics (online, etc. )

For the problem of pouring water, remember one thing: it can only be poured in one direction.

There are two ways to solve this problem, one is from 3 to 7, and the other is from 7 to 3. Details are as follows:

One,

1。 3- Filling

2。 Pour 3 into 7. At this time, 7 has 3 liters.

3。 Fill it with three more.

4。 Then pour 3 into 7. At this time, there are 6 liters in 7.

5。 Fill it with three more.

6。 Fill 3 with 7. At this time, 7 is full, and 3 has 2 liters left.

7。 Pour 7 to 10.

8。 Pour 2 liters of 3 into 7. At this time, 7 has 2 liters.

9。 Fill it with three more.

10。 Then pour 3 into 7. At this time, there are 5 liters in 7. It is also 5 liters of 10. It's done.

Second,

1。 Fill in 7 first,

2。 Invert 3 from 7. At this time, there are 4 liters left in 7.

3。 Empty 3 to 10

4。 Then count three from seven. At this time, 7 has 1 liter left.

5。 Empty 3 to 10

6。 Then count three from seven. At this time, 7 is empty and 3 has 1 liter.

7。 Fill in 7 from 10,

8。 Fill 3 from 7. At this time, there are 5 liters left in 7.

9。 All three rewind 10. At this time, 10 is also 5 liters. It's done.

So, with the latter method, you have to go backwards nine times.