Dragging to fill cells has decimal errors

[Dave Minerath]

Platform: 12" iBook G4, OS X 10.4.6, Excel 11.2.3.

When I fill in part of a column with values, select those cells, and drag
the corner to fill in the rest of the column with the data, I get what
appears to be rounding errors.

Example: I fill in a series of cells in a column with:

-10
-9.9
-9.8
-9.7
-9.6

Then I select the cells and drag downward to fill in the column with data
from -10 to 10 in 0.1 steps. I end up with some cells having a value a wee
bit large or small (on the order of +/-0.0000001 or so) with the error
getting larger as I go further down the column.

Filling in rows does the same thing.

It's a small error but last I checked, -9.6+0.1 is -9.5, not -9.60000001.
When I'm working with numbers that are accurate down to 10e-6, these errors
are pretty significant.

Anybody else seeing this problem?

 

[Bob Greenblatt]

Platform: 12" iBook G4, OS X 10.4.6, Excel 11.2.3.

When I fill in part of a column with values, select those cells, and drag
the corner to fill in the rest of the column with the data, I get what
appears to be rounding errors.

Example: I fill in a series of cells in a column with:

-10
-9.9
-9.8
-9.7
-9.6

Then I select the cells and drag downward to fill in the column with data
from -10 to 10 in 0.1 steps. I end up with some cells having a value a wee
bit large or small (on the order of +/-0.0000001 or so) with the error
getting larger as I go further down the column.

Filling in rows does the same thing.

It's a small error but last I checked, -9.6+0.1 is -9.5, not -9.60000001.
When I'm working with numbers that are accurate down to 10e-6, these errors
are pretty significant.

Anybody else seeing this problem?

First, I do not see the same thing., for me, the series is correct to the
15th decimal place up (down?) to -8.6. Then it becomes -8.5000000000010.
This is the result of round off errors in the conversion form the binary
arithmetic that Excel uses internally into decimal. Excel maintains
significance to 15 decimal digits.