I want to know if it is correct to say:
The number of participants is in the lower teens.
and whether native speakers would understand the phrase in the lower teens to mean more than 10, but less than than 15?
Having read some of the comments, I want to specify that the question concerns the number of people. I am aware what in his teens means. Someone in the comment mentioned in the lower teens was used when referring to temperature. I think it is a good start and we can continue exploring (if possible) more ways of using this phrase. Thanks for all the answers and comments.