How old is Ender at the end of Ender's game?

I'm curious to know, what is the age of Ender at the conclusion of the renowned novel "Ender's Game"? The story follows Ender's journey through intense training and strategic battles, leaving readers eager to understand the full context of his growth and development throughout the narrative. Does the text reveal his age explicitly, or do we need to deduce it from the events and timelines presented? It would be intriguing to understand the maturity and wisdom Ender possesses by the story's end, and how that might be reflected in his age.