Question

Dave can play 2 songs during his commute to work, or the same song twice. His playlist contains 5 songs. How many unique ways can he play his music?

Answer 1

If the same song is played twice there 5 ways to do this.

For two songs there are a choice of 5 songs paired with 4 other songs giving 20 choices of songs.

Total choices equals 5 + 20 = 25

If the order of the songs is not important then there would only be 10 choices of songs (first * second = second * first), however the problem specified unique ways,