### Instruction: How many possible 9-digit zip codes are possible if the first digit cannot be zero?### Response: I know that zip codes are sequences of digits, and there are 10 possible digits from 0 to 9 for each position.
But since the first digit cannot be zero, that means there are only 9 possible choices for the first digit.
For the remaining 8 positions, there are no restrictions, so there are 10 possible choices for each one.
To count the total number of zip codes, I can use the multiplication principle: multiply the number of choices for each position.
So the total number of zip codes is 9 times 10 to the eighth power, or 9 times 10^8.