Complex sentence: During "Pigs (Three Different Ones)", Waters would shout the number of the concert on the tour (such as "1-5!" for the fifteenth show) so recordings of the shows would be easy to distinguish from each other.
Split into simpler sentences: During "Pigs (Three Different Ones)", Waters would shout the number of the concert on the tour, such as "1-5!" for the fifteenth show. Waters did this so that recordings of the shows would be easy to distinguish from each other.