Answer:
17,576,000
Step-by-step explanation:
From A to Z, there are 26 possible letter characters (L).
From 0 to 9, there are 10 possible numeric characters (N)
If each standard automobile license plate number in Pennsylvania follows the pattern LLLNNNN, the number of license plates that can be formed is:

17,576,000 distinct license plate numbers can be formed in Pennsylvania.