Question

How many 7-digit telephone numbers can be formed if the first digit cannot be 0 or 1

Answer 1

8,000,000 combinations

Explanation:

Since we have 10 digits per slot, we need to remove two digits, 0 and 1, for the first slot therefore we get:

8 × 10 × 10 × 10 × 10 × 10 × 10 =

8,000,000 combinations