"The five sons do not sleep."
Translation:Quinque filii non dormiunt.
September 7, 2019
I also thought that only 1, 2 & 3 were declinable in Latin, but, e.g. 200 (ducentī, -ae, -a) is declinable
I trust the Dickinson College commentaries.
According to Lewis&Short, 900 (nongenti, ae, a) is also declinable.