sum difference

[Kaye]

When I am working in Excel I frequently have noticed simple addition math
functions not calculating correctly -- as simple as $21.26 + $ $6.80
summing up to $28.07 instead of correctly $28.06. I have checked cell
formatting on the cells affected and do not see any formatting issues that
would explain this. Has any one else ever noticed this? It's minor, but I
would like to resolve the issue if any one else has had this happen and can
offer some insight.

 

[John C]

Where do the values of $21.26 and $6.80 come from? If these are calculations,
and it is formatted to 2 decimals, then that could explain your problem.

What if $21.26 is actually $21.26443 and $6.80 is actually $6.8019, then,
when added together, they are actually $28.06633, which would appear as
$28.07.

 

[Sean Timmons]

Possibly 21.26 is really 21.2643220... and 6.80 is 6.803452

So, when you add those together, it rounds up.

 

[Sheeloo]

Following is taken from http://www.cpearson.com/excel/rounding.htm;
Under normal circumstances, Excel always stores and manipulates numbers as
8-byte "Double Precision Floating Point" numbers, or "Doubles". Excel's
internal storage of the number is not affected by the way that you may choose
to format a number for display. For example, if a cell contains the formula
=1/3, Excel always treats this value as 0.3333…, regardless of how many
decimal places you choose to display on the worksheet. Even if you choose to
display the value as simple "0.3", Excel still retains the complete number as
the value of the cell.
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So what you have observed is probably due to rounding...
If you enter the nos as you have shown then you will always get 28.06 and if
your nos are actually, say, 21.264 and 6.801 you will get 28.07...