Quite serendipitously, I came across Mr. Pearson's website yesterday, while looking up on this topic.



Several work-arounds are explained there. I have developed some on my own. However, the fact that Microsoft Excel is very poor at handling time intervals remains. A very serious feature deficiency in such a widely used software.

In explaining Time Intervals, Mr. Pearson says - "However, since Excel cannot handle negative times, you must use an =IF statement ... ". Why the hell not? A negative number for money, distance, weight, ... these are not exotic concepts in calculations. So is time. Why should 10 seconds be represented as 00:00:10 and -10 seconds result in apoplexy? (Just to make matters perfectly clear, my complaint is not with Pearson, but with Microsoft)

Have you tried posting your query on www.excelforum.com. The knowledge of the guys and girls on that sight is phenomenal on functions, formulas and formats etc.