Comment Comment by eam Permutation without repetition.The formula is:n! / (n − r)!Since there is 10 (n=10) total numbers, 0-9. And it can only be 3 (r=3) digits long. Then it would be,10! / (10-3)!* which would result in,10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1 / (7 * 6 * 5 * 4 * 3 * 2 * 1) = 10 * 9 * 8 = 720. parent eam 7 years ago
The formula is:
n! / (n − r)!
Since there is 10 (n=10) total numbers, 0-9. And it can only be 3 (r=3) digits long. Then it would be,
10! / (10-3)!* which would result in,
10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1 / (7 * 6 * 5 * 4 * 3 * 2 * 1) = 10 * 9 * 8 = 720.