There are 10 numbers in each row and 10 rows (there are 10 numbers in each column and 10 columns).

The number on the right of two adjacent numbers in a row is larger than the number on the left 1.

The next number of two adjacent numbers in a column is greater than the previous number 10.

On the one hand, this arrangement will enable students to improve and consolidate the knowledge gained in digital recognition, on the other hand, it will cultivate students' ability of observation and expression, promote the development of students' thinking and enhance their interest in learning mathematics.

Prime numbers are also called prime numbers. A natural number greater than 1 cannot be divisible by other natural numbers except 1 and itself, and is called a prime number; Otherwise it is called a composite number.

Prime numbers are used in cryptography. The so-called public key is to add a prime number to the information to be transmitted when encoding, and then transmit it to the receiver after encoding. If anyone receives this information without the key possessed by the receiver, the process of decryption (actually the process of finding prime numbers (decomposing prime factors)) will be too long, even making it meaningless to obtain information.

In The Legend of the Condor Heroes, Huang Rong once cracked the nine squares. The formula is: wear nine shoes, one left, three right, seven left, two four shoulders, eight or six is enough, and five lives in the middle.

There is also a formula: "Don't forget to fill in the middle of the rising line in turn; Put it down when loading and unloading the box, and put it left when unloading the right box; The weight is filled in the box below, as is the upper right row. " This formula is not only applicable to the nine palaces, but also to the promotion of odd-numbered nine palaces, such as the five-five diagram and the seven-seven diagram.