sztuczny-kot writes "It seems that many spreadsheets have a sort of a bug in automatic creation of arithmetic series which can be replicated as follows:
Select a cell, say A1 and input a value of 10. Then go to the cell below it (in this case A2) and input 9.8. Now select the two cells and drag the lower-right corner of the selection down to create arithmetic series. Drag until you get to cell A60. Then look at the numbers below 8.6. For example, insted of 0 you might get something like 3.5527136788005E-14. Other cells with numbers lower than 8.6 will most likely also contain a value that is somehow close to the one you would expect, but not the one. I guess that this bug might be somehow caused by floating-point number representation. Or perhaps it should be called a (rather unintuitive) computational feature and there is nothing to make fuss about?
As far as I could check, this applies to the following spreadsheets:
Microsoft Excel — versions 4.0, 97, 2007
Gnumeric 1.6.3
Open Office Calc 2.0.4"