In a country, there are four types of banknotes: 5, 10, 20 and 25 unit values. Each banknote has a serial number with more than four digits. A banknote is chosen randomly. What is the probability that the sum of the four last digits of the serial number is bigger than the banknote unit value?
Note:Four banknote types, and all the serial numbers (...0000 - ...9999) can be chosen with equal probability.
Enter your answer as a simplified fraction. Example:12/23
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