[Figure] Children's exercise book, there is such a trap? !

Today Sunday, my son ran out to play with his classmates as soon as he finished his homework at noon, and has not come back yet. At five o 'clock in the afternoon, another of his classmates came to him and said that he wanted to know a problem in the homework. I said that my son was not at home, but you can have a look at his homework. As a result, after I opened his homework book, I accidentally found that this math problem was not completely written, and it was openly written behind: Please call 16890168 for detailed explanation. I was immediately angry, how could such a sick thing happen?

I don't know which level of education department approved or approved this approach, but I guess it was the idea of a group or department that was crazy about money. Many people are saying that the Japanese are perverted, but I would like to ask, when did Chinese education become so perverted??