Final answer:
There are 1,000,000 potential 6-digit personal ID numbers assuming IDs can start with zero. If IDs cannot start with zero, then there are 900,000 unique IDs possible.
Step-by-step explanation:
If every employee at the company is assigned a 6-digit personal ID number, to find out how many potential employee ID numbers there are, we must consider that each digit in the ID number can be any digit from 0 to 9. There are 10 choices (0 through 9) for each digit.
Since there are 6 digits in each ID number, the total number of possible combinations would be calculated by multiplying the number of choices for each digit. Therefore, we do this calculation: 10 x 10 x 10 x 10 x 10 x 10 which equals 1,000,000. This represents the total number of unique 6-digit ID numbers possible, assuming the ID can start with a zero.
However, if an ID can't start with zero, the first digit would have only 9 choices (1 through 9), so the calculation would be 9 x 10 x 10 x 10 x 10 x 10, resulting in only 900,000 possible unique IDs.