(but it could be cool to tell the kids at school!)
My age = x
Last two digits of the year I was born = y
This year = 2011
So my age is either 2011 - (1900+y) = x
or my age is 2011 - (2000+y) = x
However, there are probably just a few people in the world this doesn't work for.....
If I was born in 1899 -= i.e I'm 112 years old....
So my age is 2011 - (1800+y) = x