Harlan pointed this out in a comment on the fluent UI strategy post, having spotted it in the newsgroups.
If you type
=850*77.1 in a cell it results is 100,000 rather than the more traditional 65,535.
It seems many combinations that result in 65,535 have been updated to 100,000. (could it be a covert metrification attempt?)
This looks a bit like a new-for-2007 optimisation that has a border case error, or an off by one error. How wide the impact might be I suspect we will never find out.
I suspect this only affects in cell cal…. Whoooaa scratch that, this is a bit more serious.
Put any 2 numbers that when multiplied give 65,535 or 65,536 in 2 different cells multiply them in another, in about 1 out of 10 times it will give the wrong answer (100,000 or 100,001).
I did this in 2003:
col A = row()
col b = 65,535/A1 or A2 etc
copy and paste (values – it did that by default??) into 2k7 and in col C put A*B and let the fun begin.
In col D put =C1=100000 – it never says true. And in most calcs it seems to know its really 65,535 or 6.
You can also do combinations of multiply and add to get wrong answers.
How serious is it? I don’t know – do you?
What caused it? I don’t know – do you? it does look like some bit diddling rather than a simple overflow though.
Am I glad I’m still using 2003? oh yes. Are you?