Question

The digits 3, 4, 5, and 6 are used to form a four-digit code. No
repeated digits are allowed. How many codes are possible?

Answer 1

3,6,5,4
4,5,6,3
5,6,3,4
6,3,5,4
4,6,3,5
3,5,4,6
6,4,5,3
I hope I answered it right