How many international direct-dialing numbers are possible if each number consists of a four-digit area code (the first digit of which must be nonzero) and a five-digit telephone numbers (the first digit must be nonzero)?

Question

a. 567,000,000
b. 486,000,000
c. 1,053,000,000
d. 729,000,000
e. 810,000,000

Thank you for helping.

Answer 1

9*10^3 * 9*10^4