Answer:
1. 8.58, 8.508, 7.5, 7.058
2. 439.612, 439.261, 439.216, 439.126
Explanation:
Prioritize the numbers that have a higher digit at a higher position. Just for fun:
In[1]:= ReverseSort[{8.508, 8.58, 7.5, 7.058}]
Out[1]= {8.58, 8.508, 7.5, 7.058}
In[2]:= ReverseSort[{439.216, 439.126, 439.612, 439.261}]
Out[2]= {439.612, 439.261, 439.216, 439.126}