When was the band of the extended play To Be One officially announced?
1X1=1 (To Be One): 1X1=1 (To Be One) (also known as 1×1=1 or To Be One) is the debut extended play by South Korean boy group Wanna One, a project group created through the 2017 Mnet survival show, "Produce 101 Season 2", composed of eleven trainees from different entertainment companies that will promote for 18 months under YMC Entertainment. Produce 101 Season 2:  On June 16, 2017, the season finale was broadcast live, announcing the final 11 members who would debut, as well as the official group name Wanna One.
June 16, 2017