Question

Compute the permutations and combinations.

How many two-digit, positive integers can be formed from the digits 1, 3, 5, and 9, if no digit is repeated?

A. 12
B. 16
C. 24

Answer 1

permuation is no repeats
that is n!
2 digits
with the 4 numbres
so
first number can be 4 possible numbers
2nd can be 3 because 1 has been used

so 4*3=12
12 is answer
A is answer

Answer 2

the correct answer to this question is 12