Permutations and Combinations in Algebra 1??? I don't understand how to do these.

Question

anonymous · Answer

A seven digit telephone number can begin with any digit except 0 or 1. There are no restrictions on digits after the 1st digit. How many possible choices are there for the first digit? For each digit after the first digit? How many 7 digit numbers are possible?

anonymous · Answer

The first two questions I know the answers are 8 and 10.

anonymous · Answer

I don't understand that.

anonymous · Answer

Ok, so basically you have 1 of the 7 digits which has a possibility of 8 different numbers. Then six numbers after that, that can be 10 different numbers.