What is the probabilty that the first 2 numbers of the serial number on a doller bill will exactly match?

the last two numbers of that serial number?What is the probabilty that the first 2 numbers of the serial number on a doller bill will exactly match?
Assuming the digits 0-9 are equally likely to occur in any of the four positions, the probability is 1/100.





To see why, consider that you have a bill with some two digits as the first two. Now, there are 100 possibilities (0-99) for the last two digits, only one of which matches the first two.