Every street in Canada is assigned a postal code. A postal code is made up of 3 letters and 3 digits that alternate. How many different postal codes can be created given the following conditions?
a) There are no restrictions.
b) The first letter must be S.
c) The first letter must be S and the first digit must be 7.
a) So if you are using 26 letters and 10 digits (0-9) would it be 26 * 10 = 260?
OR would it be 26 * 26 * 26 = 17576, 10 * 10 * 10 = 1000, so with no restrictions, there would be 18576 different postal codes?
b) and c) I don't understand how to do these.