Excel 2007 warning - serious multiplication bug

[Mark R]

This just got passed to me as a heads-up. I don't have excel 2007, so can't verify it myself. However, several trusted people have verified it.

If you multiply two numbers so that the product is 65535, then the answer is reported as 100000.

Examples:
=5.1*12850
=10.2*6425
=20.4*3212.5
=40.8*1606.25
=77.1*850
=154.2*425
=212.5*308.4
=308.4*212.5
=425*154.2
=SUMPRODUCT(850,77.1,2,0.5)
etc.

If you are using Excel 2007 spreadsheets that perform multiplications you should double check your calculations by an alternative method.

Note that this is more than just a simple display bug - the incorrect answer may be propagated through dependent calculations.

Example
A1: = 5.1 * 12850
B1: =A1+1

B1 will be evaluated as 100001.

 

[archcommus]

Just verified it with your first example. Guess they need a patch pretty quickly.

 

[BladeVenom]

It's not a bug; it's a design feature.

 

[stash]

Note that this is more than just a simple display bug

Actually, this is a display bug:

http://blogs.msdn.com/excel/ar...tion-issue-update.aspx

 

[Mark R]

Originally posted by: stash

Note that this is more than just a simple display bug

Actually, this is a display bug:

http://blogs.msdn.com/excel/ar...tion-issue-update.aspx

Apart from the fact, that if you perform calculations based on the result of that cell, they may also be wrong.

See example above, which gives 100001, when the correct answer would be 65535.

That blog article appears to be wrong.

 

[tatteredpotato]

Originally posted by: Mark R

Originally posted by: stash

Note that this is more than just a simple display bug

Actually, this is a display bug:

http://blogs.msdn.com/excel/ar...tion-issue-update.aspx

Apart from the fact, that if you perform calculations based on the result of that cell, they may also be wrong.

See example above, which gives 100001, when the correct answer would be 65535.

That blog article appears to be wrong.

He explains that adding one is still close enough to be part of the bug. Try adding 2.

 

[Dfere]

Yes, I have run into this . (I am a CPA). I thought this was just my install. I also noticed a few other times where multiplication did not work. And addition. Unfortunately, I really had not logged any of this stuff before.

I always check my work through an alternate calculation which is where I caught these. I had to run a 10-key to confirm correct amount (always at my side still). I will try to keep on the lookout for specifics....... and post here.

In any spreadsheet, you really should check your work. Not just Excel- just basic GIGO 🙂