How do I add a column of numbers only if the dates in another column are the
same?

EX:

A B
c
1 1/9/08 16
16
2 1/9/08 24
40
3 1/10/08 32
32
4 1/10/08 36
68
If I place the formula in column "C" I want the dates that are the same to
continuously add until the next date occurs