For years, telephone area codes in the United States and Canada consisted of sequence of three digits. The first digit was an integer between 2 and 9; the second digit was either 0 or 1; the third digit was any integer between 1 and 9. How many are codes were possible? How many area codes starting with a 4 were possible?

http://www.bilkent.edu.tr/~math250/Solution%20set1.pdf