I had a few questions about making an excel sheet to calculate a golf handicap for my personal use. I searched everywhere but couldn't find what I am looking for.

Currently I have 6 columns:
A - Date
B - Course
C - Score
D - Slope
E - Rating
F - Differential

I enter all the information for A-E and then F calculates accordingly. I have all the formulas in and it works fine, but when I add a new score I have to sort the cells and then change a range in the formula to calculate the handicap. Basically I'm looking for a way to find the 20 most recent dates and then using those 20 most recent dates find the 10 best differentials. Any suggestions? Thanks in advance!