So i've jumped midway into a course and there are one or two topics I was never there for. On a take home review for me to know what kind of problems to expect on an upcoming test there were the following two problems that I wasn't sure how to approach:

1) suppose we have an alphabet A = {a through z, A through Z, and 0 through 9} (63 characters).

a)Identifiers have NO MORE THAN 8 characters, the first character is upper or lower case alphabetical, successive characters can be any element of A.

How many distinct identifiers are possible? What counting principles are being used?

b) Suppose you are now allowed to have a single _ as the first character provided the second character is upper or lower case alphabetical, but still 8 or fewer characters in an identifier. How many additional identifiers are now possible? What counting principle is being used?

2) Suppose a class has 26 male, and 9 female students. The teacher is forming a discussion panel of 6 members.

a) How many different discussion panels are possible?

b) If the teacher wants 4 males and 2 females on the panel, how many different discussion panels are possible?

Again this is to help me review so if possible I dont want just the answer but someone to spell out how you would walk through this problem so that I can do another one like it in the near future (although the answer would also help so I can double check myself). Thanks for any help! Im aware this isn't necessarily a calculus problem but I really dont know what topic it would fall under.