Question

What is the median for the following data set: 10 8 16 2

Answer 1

It's 9 -- the mean between 8 and 10

'Median' is defined as the middle value, once de data set is ordered according to value. So in your case this would give 2 8 10 16.
If there are two middle values, the median is defined as the mean between them.
With larger data sets this usually doesn't matter much, as the middle values tend to be close. E.g. the heights of say 1000 adult males, or the income of the people of a city.
In a data set as small as yours I would hesitate to give any center or spread measures.
Challenge: try and make a box plot of this!