Hey guys I have a few questions that have stumped me.. either because I'm wrong or the answer key is wrong.

1) Joanne prefers classical and pop music. If her friend Charlene has five classical CDs, four country and western CDs, and seven pop CDs, in how many orders can Joanne and Charlene play the CDs Joanne likes?

2) Suppose you are designing a coding system for data relayed by a satellite. To make transmissions errors easier to detect, each code must have no repeated digits.

a) If you need 60 000 different codes, how many digits long should each code be?

b) How many ten-digit codes can you create if the first three digits must be 1,3, or 6?

For the first one I said P(16,12) but that wasn't the right answer.

The second one I have no clue