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Johnny has a locker combination with 1 letter followed by three digits. None of the digits can repeat themselves. How many combinations are there in the sample space? (Theoretical Probability and Simulations) Help me find the answer.

Verified Answer :

First, what letter can it be at the beginning?

English Alphabet has 26 letters, so we have 26 possibilities

26

then it can be any of 10 digits

26
10=260

then any of the remaining 9 digits:

26109

then any of the remaining 8 and 7 digits:

2610987=131040

so the solution is: 131040 possible combinations!