2017 AMC 8 Problems/Problem 20
An integer between and , inclusive, is chosen at random. What is the probability that it is an odd integer whose digits are all distinct?
There are options for the last digit, as the integer must be odd. The first digit now has options left (it can't be or the same as the last digit. The second digit also has options left (it can't be the same as the first or last digit). Finally, the third digit has options (it can't be the same as the three digits that are already chosen).
Since there are $9000 total integers, out answer is