What is the formula of the law of wide-angle collocation in senior two mathematics?

The formula of the law of wide-angle collocation in senior two mathematics is as follows:

"Unit" positioning, "Ten" positioning and exchange method in positioning methods. For example, 1, 2,3 form a two-digit number, and the ten digits and the single digits of each two-digit number cannot be the same.

"Company" positioning method: locate 1:2 1, 31in the company; Position 2 in the unit:12,32; At the position of the unit 3:13,23.

"Decimal digit" positioning method: locate 1: 12,13 in the decimal digit; Position 2:2 1 23 in the tenth; The tenth position is 3:3 1, 32.

Exchange method: 12 to 21; 13 is 31; 32 minutes and 23 seconds.

So it can be seen from the above method that 1, 2,3 can form six two-digit numbers.

"Positioning method": 1. Positioning the word "Sun": Sun Walker, Sun Walker; Secondly, the word "walk" is defined as: the grandson of the walker, the grandson of the walker; Finally, the word "zhe" is defined as "Sun Zhe" and "Sun Zhe".

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