A five-digit integer will be chosen at random from all possible positive five-digit integers. What is the probability that the number's units digit will be less than 5? Express your answer as a common fraction.
The number of five-digit integers with units digit less than 5 is 36,000.
The number of five-digit integers is 90,000.
Therefore, the probability is 36,000/90,000 = 2/5.