ForEach extension on IList

Despite the existance of all that fancy lambda stuff, I would still write this the old-school way:

var studentList = new List<student>();

foreach (var st in studentList) {
   if (st.Age == 0) st.AgeInMonths = DateTime.Now.Subtract(st.DOB).TotalDays / 30);
} 

My "solution" needs ~160 characters versus ~174 characters in the op version (without the generic method). I also think it's easier to read for the majority of people - and that's the important point.