According to Ender's Game, Ender was six years old.
According to Ender's Shadow, Ender was five.
You can choose which answer you want to, but I go with "five" because Orson Scott Card says in both of his series THE SHADOW COMPLEX and the original ENDER SERIES that Ender was five, so Orson Scott Card must have corrected his mistake early on.
MLB player Ender Inciarte bats left.
MLB player Ender Inciarte throws left.
As of the 2014 MLB season, Ender Inciarte is 23 years old.
Ender is approximately 12 years old when he returns to battle school in "Ender's Game" after being on Earth for some time.
Kornelia Ender is 52 years old (birthdate: October 25, 1958).
Ender becomes homesick when he receives a letter from his sister Valentine because it reminds him of his family and the life he left behind on Earth. This triggers a sense of nostalgia and longing for the familiarity and comfort of his previous life.
Petra Arkanian is about 12 years old in "Ender's Game".
Old age.
He gets the bottom bunk by the door. It's because he was the last one in and it was the only one left.
Bean, as mentioned in ENDER'S SHADOW, was about seven when he went into Dragon Army and fought in the Third Invasion. To check my answer, and also because it is a genuinely good book, read ENDER'S SHADOW.
Mazer Rackham
Abe Lincoln was 21 years old when he left Indiana and moved with his family to Mcon County, Illinios.