Interesting mathematical questions

Today, on Facebook and Alibaba Cloud
We can see that someone has taken this topic.

This problem can be solved by pre-school children in 5-10 minutes, by programmers-in 1 hour, by people with higher education... well, check it yourself! :)

8809 = 6
7111 = 0
2172 = 0
6666 = 4
1111 = 0
3213 = 0
7662 = 2
9312 = 1
0000 = 4
2222 = 0
3333 = 0
5555 = 0
8193 = 3
8096 = 5
7777 = 0
9999 = 4
7756 = 1
6855 = 3
9881 = 5
5531 = 0

2581 =?

This topic is interesting.
Before learning, the child can solve the problem as long as he is five to ten minutes old.
However, programming takes an hour
It even implies that people with higher learning skills may spend more time.
I thought about it later.
If you don't want to come up, Google will find a website
The author said that he is a data doctor, but he cannot solve it. His wife just gave a look at the answer.

I'm not angry, so I can't help looking at the response.
Let's take a look at how long it will take to find the answer.

If you can't help it, press the Skip button to see the problem progress.

I spent a lot of time finding a solution.
If there is no accident, it should be solved from the perspective of the children before learning
In fact, we can only learn more things.
More reasoning from the perspective of Artificial Intelligence

I'm more curious about why don't I mention programming?
Later I discussed it with my colleagues in the Mathematics Department (he is also a programming program ).
Finally understood

His approach is as follows:

The value 0-9 indicates another number.
For example, 8 represents x, 0 represents y, and 9 represents z, and the 8809 represents x + y + z.
We know that x + y + z = 6
Next, you only need to extract the values of x, y, and z.
We can find out the 2581 solution required by the topic.

Therefore, we can
1111 = 0, 2222 = 0, 3333 = 0, 5555 = 0, 7777 = 0
Obtain
1 → 0, 2 → 0, 3 → 0, 5 → 0, 7 → 0

Again from 0000 = 4, 6666 = 4, 9999 = 4
0 → 1, 9 → 1

We do not know the Representative Values of 4 or 8.

Starting from 8096 = 5 (False 8 = x)
X + 1 + 1 + 1 = 5
X + 3 = 5
=> X = 2

=> 8 → 2

Except for 4, we have found the value.

0 → 1
1 → 0
2 → 0
3 → 0
5 → 0
6→1
7 → 0
8 → 2
9 → 1

It doesn't matter. Only 2581 =?
Directly substitute 2 → 0, 5 → 0, 8 → 2, 1 → 0
0 + 0 + 2 + 0 = 2

So 2581 = 2

Well, it's very difficult to get started. I also think it's very annoying.
It feels like a programmer in programming.
Well, it's a question. How can a child be promoted like this before learning?

As a result, the answer is actually confusing.
I used this solution, called the pictogram XD.
In fact, this formula only requires several circles !!!!

1, 2, 3, 4, 5, and 7 do not have circles, so they are all 0
0, 6, and 9 have a circle, so they are all 1
8 has two circles, so it is 2

So 2581 = 2
Is there something simple and straightforward...