The law of mathematics discovery in the third grade of primary school is 3.7. .2 1.3 1
Hello, according to the original question-looking for the law of mathematics in the third grade of primary school 3, 7, (? ), 2 1, 3 1. It can be inferred that the middle number is 13, which is an increasing law, and the differences between them are 4, 6, 8 and 10 respectively. So the middle number is exactly equal to 6+7= 13.