Calculating failure time

[DRkidd22]

Hello,

I have to do this thing with a huge file that has about 7K rows. I'm trying to figure out if someone here can help me out, as usual.
Basically I have three columns, serial number(A), Parameter Value(B), and Date(C). These basically are reports for a serviced product (shortened here for ease). Column A is the products serial number and Column B is the serial number of a part in the product, if that part's serial number changed it means it got replaced for some reason. So my goal is to figure out how long that particular part's serial number was on the field before it failed.

For example I can calculate that in product serial number 1029 the part with serial number 07011910 was installed on jul 01 2010 (row 6) and replaced on mar 2 2011 (row 9). Pretty easyli I can figure out what the life, in days, of 07011910 was before it got replaced. But the thing is that the data is all over the place, some may have never been replaced as you can see from the attached sheet. Any ideas will be appreciated on how to tackle this one. I got a long way to go here.

see attached below

fldLife.xlsx

[oeldere]

If i understand you well, you only want to find the result in cel E20?

see the yellow cells.