A quirky behavior of OpenOffice.org Calc was observed. I uploaded the sample spreadsheet here [link to .ods] .
Would be great to know if someone else can reproduce it.
The first 3 columns have three dates and cell D2 uses the DAYS function to find the difference between the dates. Since the result is accurate, we also put that in cell D4 by-hand. We repeat a similar set of actions for E2 and E4.
Having done that, we divide E2 by D2 and E4 by D4 to obtain the results in F2 and F4. The results in G2 and G4 are obtained by F2 by 15 and F4 by 15 respectively. The contents of G6 are input by-hand.
For the cells H2, H4 and H6, the data is input by hand and I2, I4 and I6 are obtained by multiplying H2, H4 and H6 by G2, G4 and G6 respectively. Check the results obtained
All of the above would be obvious if you check the formula bits in the spreadsheet.
The real fun of course is in the remaining rows. G8 is obtained as a result of the expression F8*15 (note: G2 was 15*F2) which is somewhat different and thus we end up with different results on I8.
Check out the spreadsheet. It is fun. The OO.o issuezilla does not seem to work for me, so shall file a bug later.