1, 2, 3, 4, 5, 6 synthesize these six arrays into four numbers (for example,11,11/2,1)

Because four numbers are a group, there is no need to consider the order after combination. So it can be equated with drawing lots.

If the numbers are not repeatable,

There are six possibilities for the first number and five possibilities for the second number. . And so on. .

6*5*4*3 == 360

If it can be repeated, it can be regarded as a question of putting it back into the category after drawing lots.

6*6*6*6 == 1296