2! Is the factorial calculation, is the factorial calculation of 2, 2! =2。 The specific calculation process is as follows:

2! =2x 1=2。

Calculation method of factorial:

When the factorial number is greater than or equal to 1, use the formula n! =nX(n- 1)x(n-2)x？ X3x2x 1 for calculation.

When the factorial number is equal to 0, use 0! = 1 calculation.

When the factorial number is less than 0, the formula is meaningless.

Extended data:

With "m! ! "Express delivery.

When m is a natural number, it means the product of all positive integers not exceeding m and having the same parity with m, such as:

When m is a negative odd number, it means the reciprocal of the absolute product of all negative odd numbers whose absolute values are less than their absolute values.

When m is a negative even number, m! ! Does not exist.

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