probability of combining numbers

Question

How many four digit numbers can be formed from the numbers 1,3,4,6,8, and 9 if repetition of digits is not allowed

Answer 1

For the first digit, there are 6 possible numbers that could be in that position. Since there is no repetition, there are 5 options for the second digit, 4 for the third digit and 3 for the fourth. The get the number of options, multiply the possibilities for each digit together.

(6)(5)(4)(3) = 360 four digit numbers can be formed