How many different seven-digit telephone numbers are possible if no number may begin with 0?.....the answer is 9,000,000 but I'm not sure how to get that, plz explain:)

Answer 1

first number could be 9 different digits, but after that we can use 10 different ones each time
so
9x10x10x10x10x10x10 = 9 000 000

Answer 2

Ok thank you:)