After trying a variety of different formulas for returning the last numeric value in a column, I settled on the following two.
=VLOOKUP(9.99999999999999E+307,A:A,1) or =INDEX(A:A,MATCH(9.99999999999999E+307,A:A))
Both of these formulas work very well and are still able to return the last numeric value even if the range contains blanks, error values (like #N/A), and text values.
The value 9.99999999999999E+307 is the largest number you can enter in a cell. The range doesn't have to be a full column. You could use B5:B100 instead of A:A.