Kelly made sure the crowd were involved, encouraging all 80,000 to sing along with her This image appears in the gallery:One Direction, Ariana, Avicii & More! The MUST-SEE Pictures From Capital's Summertime Ball 2015 72. Kelly made sure the crowd were involved, encouraging all 80,000 to sing along with her Picture: Joe Okpako 171 images See the full gallery: One Direction, Ariana, Avicii & More! The MUST-SEE Pictures From Capital's Summertime Ball 2015