teens

The number of people at the meeting was in the teens.

She is in her teens.

2010, Michael G Cunningham, “The 20th Century's aughts and teens: OPERETTA”, in Gilded Songs (Berlin to Bacharach): The Gig Instrumentalist's Guide to the Golden Era of American Popular Song (1920 to 1979):

Although it was a scorching desert by day, temperatures could drop as low as the teens at night.