A stands for factorial, A3 2 (base 2 above 3) is equal to 3*2, C stands for the number that meets the requirements from the total, and C3 2 (base 2 above 3) is equal to A3 2 (base 2 above 3) divided by A2, 2.

C26=6x5/(2x 1).

A26=6x5 .

In the case of a, the upper 2 is equivalent to the number of digits, and then multiplied by the lower 5. In the case of 2, it is equivalent to multiplying by 2, that is, 5×4.

If it is C, it is divided by 2 on the basis of A! , which is 6x5/(2x 1).

Probability; possibility

It is a numerical value to measure the possibility of accidental events. If the experiment is repeated many times (denoted by X), the accidental event (denoted by A) appears many times (denoted by Y). Take X as the denominator and Y as the numerator to form a numerical value (denoted by P). In many experiments, P is relatively stable at a certain value, and P is called the probability of a certain occurrence. If the probability of accidental events is determined through long-term observation or a large number of repeated experiments, it is statistical probability or empirical probability.