The permutation and combination of four numbers 1234 is composed of: one two three four twelve thirteen fourteen twenty-three twenty-four thirty-four one hundred and twenty-three . How many combinations are there? And how are they calculated? There is no requirement for the order of arrangement

The permutation and combination of four numbers 1234 is composed of: one two three four twelve thirteen fourteen twenty-three twenty-four thirty-four one hundred and twenty-three . How many combinations are there? And how are they calculated? There is no requirement for the order of arrangement

C41+C42+C43+C44=4+6+4+1=15
The first digit is a superscript and the second is a subscript. C is a combination operation

How many combinations are there for the six numbers 123456?

6!=6x5x4x3x2x1=720

123456 is a combination of two numbers. There are several methods

If it is a combination, C (2,6) = 15
If the real permutation is a (2,6) = 30