In a New York State daily lottery game a sequence of three d

In a New York State daily lottery game, a sequence of three digits (not necessarily different) in the range 0-9 are selected at random. Find the probability that all three are different.
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Solution

1st spot can be chosen from (0 to 9 ) = 10 numbers

2nd spot can be chosen from 9 numbers

3rd spot from 8 numbers

so total possible ways are

10 * 9 * 8 = 720 ways

and total number combinations available are 10*10*10 = 1000

so probability that all three are different is 720/ 1000 = 0.72