I'm not sure if this is me or Excel. can some of you guys try the following and let me know the result

In a new worksheet
1/ type the value -0.25 into cell A1
2/ type the formula =A1+0.01 into cell A2
3/ Copy the formula into cells A3:A26
4/ Select the range A1:A26 and change the number format to 16 decimal places.

Do you see anything wierd starting at cell A16?

The value should be -0.1 ( = -0.25 + 15*(0.01)) but i get the value -0.0999999999999999

So is it just me or can excel not add?