Assign a value to a text

Hey everyone. In cell iC, where C is the third column and i is any integer greater than 2, there exists text. I assign the text to the cell, and it has the form "Payday (xx hrs; mm/dd to mm/dd)." I want to assign a value of xx to this cell so when I highlight cells from iC to jC (2 < i < j), it gives me the sum of all the xx's in the status bar.
I tried doing this: ="Payday ("&xx&" hrs; mm/dd to mm/dd)" but that didn't work. :\
I can't make a new column just for the value xx corresponding to each of its adjacent cells because not all cells in column C have this format, making the new column sparse. I was wondering if I could assign a value to a cell that exists in a text in that same cell. Can anyone help me out?

Thanks in advance.

I'm not exactly sure what you're trying to do. Do you want the cell to display the value of xx where the cell already contains a formula whose result is "Payday (xx hrs; mm/dd to mm/dd)"? Could you send an example of the current formula and the resulting value displayed?

-Greg