To find the median of a set of numbers, you first need to arrange the numbers in ascending order (if they aren't already), and then find the middle number.
The numbers you provided are: 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5
There are 9 numbers in this set, which is an odd count. Therefore, the median is the middle number, which is the 5th number in this ordered list.
The 5th number is 2.5.
Thus, the median is 2.5.